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ACCESSION #: 9907290189

FOXBORO
The Foxboro Company
Foxboro, MA 02035-2099
United States of Americal
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 15, 1999

Mr. Bob Stransky
United States Nuclear Regulatory Commission
Event Assessment
1155 Rockville Heights
Rockville, MD 02852

SUBJECT: Our notification to you at 10:00 AM July 9, 1999

Dear Mr. Stransky,

In accordance with 10CFR21 this letter is to inform you that The Foxboro Company has today sent the enclosed letter to 48 locations identified as being customers for a potential defect with N-2A0-L2C-R or N-2A0-L2C-R with ECEP 10273, Contact Output Isolator cards that may contain specific N0152CK or C0147SS relays. Please note that our notification now has been extended to include customers potentially receiving relays manufactured from 1977 (previously 1981) through 1993. This was done to ensure the complete coverage of the issue based on further information from our vendor.

  Sincerely,
  The Foxboro Company

George Robert Johnson
Director, Corporate Quality Assurance and Product Safety

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

REPRESENTATIVE SAMPLE

July 14, 1999

<<Title>> <<FirstName>> <<LastName>>

<<JobTitle>>

<<Company>>

<<Address1>>

<<Address2>>

<<City>>, <<State>> <<PostalCode>>

Reference: Your Purchase Order Number: <<PurchaseOrderNo>>
Foxboro Sales Order Number: <<SalesOrderNo>>
Quantity:<<Quantity>>
Model: N-2A0-L20-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

In some applications, The Foxboro Company also utilizes a 2 Form C version of this relay (Foxboro part number C0147SS). Both N0152CK & C0147SS relays utilize the same materials and construction techniques. Although no failures of the C0147SS relays from shunt paths have occurred, the potential for such a failure does exist in the same low voltage & low current applications. For this reason Foxboro is recommending that those Contact Output Isolators which utilize C0147SS relays be included in the following recommended corrective actions. Such corrective actions should be evaluated immediately and Implemented as soon as possible.

The Foxboro Company is recommending that each customer inspect for, and replace, N0152CK & C0147SS relays manufactured by Potter & Brumfield which display manufacturer's date codes between 7707 and 9352, with those replacement relays manufactured by Communications Instruments Inc. The date code is indicative of the year of manufacture first, followed by the calendar week of the indicated year.

Inspection for those relays supplied by Potter & Brumfield will require removal of the N-2A0-L2C-R card from the nest. Visual inspection of the relay package allows easy identification of those relays manufactured by Potter & Brumfield. The sides of the relay and are stamped with the Potter & Brumfield name, the Potter & Brumfield part number, the appropriate Foxboro part number (N0152CK or C0147SS), and the coil resistance. In some instances the side of the relay may display the manufacturer's date code, otherwise the relay has to be removed from the relay socket, after which the date code can be found on the base of the relay. If the relay has a manufacturer's date code marking beginning with 7707 through and including 9352, it should be removed and replaced with one manufactured by Communications Instrument Inc.

Relays stamped with "SIGMA" on the top, or Communications Instruments Inc on the side, do not require replacement.

Replacement N0152CK or C0147SS relays may be obtained by contacting the Foxboro Response Center at 1-888-Foxboro (1-888-369-2676). You may also feel free to contact the Foxboro Response Center if you have any questions regarding this notification.

The U.S. Nuclear Regulatory Commission has been informed of this potential defect. The Foxboro Company sincerely regrets any inconvenience this potential defect may cause you and trusts that our actions will completely resolve this matter to your satisfaction.

  Best regards,

The Foxboro Company
George Robert Johnson
Director, Corporate Quality Assurance and Product Safety


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Design & Vendor Documents Mgr., TMI
GPU Nuclear Corporation
P.O. Box 485
Middletown, PA 17057

Reference: Your Purchase Order Number: See Attached Sheet
Foxboro Sales Order Number: See Attached Sheet
Quantity:123
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

General Electric Company
1100 Western Avenue
Building 2-3
Lynn, MA 01910

Reference: Your Purchase Order Number: 089T376171 N-062 & 089T376175N032, A89-Q9-328283-G800
Foxboro Sales Order Number: 791349288, 84N36475
Quantity:5
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

General Electric Company
1285 Boston Avenue
Bridgeport, CT 06602

Reference: Your Purchase Order Number: 194BFO-74009, 194BFO-94034
Foxboro Sales Order Number: 771316583, 791328101
Quantity:4
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147S8 relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

General Electric Company
FSO Nuclear
P.O. Box 9429
San Jose, CA 95157

Reference: Your Purchase Order Number: 205-831-455, 205-AH921REV3, 205-XG015, 205AJ113
Foxboro Sales Order Number: 83N27384, 77N26313, 80N27721, 78N61787
Quantity:18
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Mr. John R. Sampson
Vice President Indiana Michigan Group
Indiana Michigan Power Company
500 Circle Drive
Buchanan, Ml 49107

Reference: Your Purchase Order Number: 00777-821-8X, C-8741, C-8741 REPL
Foxboro Sales Order Number: 88N34665, 921712687, 921721688, 93F29761
Quantity:156
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Mr. John F. Franz, Jr.
Vice President, Nuclear
IES Utilities, Inc.
200 First Street, SEL
P.O. Box 351
Cedar Rapids, IA 52406-0351

Reference: Your Purchase Order Number: S40596, S75317
Foxboro Sales Order Number: 88N42018, 93F07784
Quantity:4
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform You of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed Contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with t n plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Q.A. Department
Duane Arnold Energy Center
3277 DAEC Road
Palo, IA 52324

Reference: Your Purchase Order Number: S40596, S75317
Foxboro Sales Order Number: 88N42018, 93F07784
Quantity:4
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Mr. John H. Swailes
Vice President Nuclear Energy-Cooper Nuclear Station
Nebraska Public Power District
P.O. Box 98
Brownville, NE 68321

Reference: Your Purchase Order Number: 186900, 189546
Foxboro Sales Order Number: 81N52062, 81N56488
Quantity: 3
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile+ 1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Supplier Q.A.
Nebraska Public Power District
P.O. Box 98
Brownville, NE 68321

Reference: Your Purchase Order Number: 186900, 189546
Foxboro Sales Order Number: 81N52062, 81N56488
Quantity:3
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Nevada Power Company
P.O. Box 230
Las Vegas, NV 89151

Reference: Your Purchase Order Number: RG4-108 Foxboro
Sales Order Number: 81N65372
Quantity: 5
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Mr. James Knubel
Chief Nuclear Officer
Power Authority of the State of New York
123 Main Street
White Plains, NY 10601

Reference: Your Purchase Order Number: 89-1411,87-IP-3174, 88-IP-0053,
88-IP-0719, 89-IP-0005, S9000471, 86-3989 86-5284, 87-5795
Foxboro Sales Order Number: 89F03657, 87N46320, 87N59811,
88N36149, 88N49659, 90F34101, 86N51407, 88N36186
Quantity:20
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Technical Services Director J.A. Fitzpatrick Nuclear Power Plant
P.O. Box 41
Lycoming, NY 13093

Reference: Your Purchase Order Number: 89-14111, 87-5795
Foxboro Sales Order Number: 89F03657, 88N36186
Quantity:3
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Quality Services Supervisor
New York Power Authority
P.O. Box 215 Buchanan, NY 10511

Reference: Your Purchase Order Number: 87-IP-3174, 88-IP-0053,
88-IP-071989-IP-0005, S9000471, 86-3989 86-5284
Foxboro Sales Order Number: 87N46320, 87N59811, 88N36149,
88N49659, 90F34101, 86N51407
Quantity: 17
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Procurement Q.C. Engineer
New York Power Authority
Indian Point 3
P.O. Box 215
Buchanan, NY 10511

Reference: Your Purchase Order Number: 87-IP-3174, 88-IP-0053, 88-IP-071, 86-3989 86-5284
Foxboro Sales Order Number: 87N46320, 87N599811, 88N36149, 88N49659, 90F34101, 86N51407
Quantity:17
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Quality Assurance
New York Power Authority
P.O. BOX 215
Buchanan, NY 10511

Reference: Your Purchase Order Number: 87-IP-3174, 88-IP-0053, 88-IP-0719, 89-IP-0005, S9000471, 86-3989 86-5284
Foxboro Sales Order Number: 87N46320, 87N59811, 88N36149, 88N49659, 90F34101, 86N51407
Quantity: 17
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Mr. John H. Mueller
Senior V.P. and Chief Nuclear Officer
Niagara Mohawk Power Corporation
2nd Floor Operations Building
P.O. Box 63
Lycoming, NY 13093

Reference: Your Purchase Order Number: see Attached Sheet
Foxboro Sales Order Number: See Attached Sheet
Quantity:79
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Mr. M.D. Wadley
VP-Nuclear, Chief Nuclear Officer
Northern States Power Company
414 Nicollet Mall
Minneapolis, MN 55401

Reference: Your Purchase Order Number: 10040-J-300QAC, D25425MQ CHANGE 001, M005217
Foxboro Sales Order Number: 81N59715, 84N42554, 80N40432
Quantity:17
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Olin Corporation
2400 Buffalo Avenue
Niagara Falls, NY 14302

Reference: Your Purchase Order Number: NF-87728
Foxboro Sales Order Number: 81N45065
Quantity:2
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Mr. W. Gary Gates
Vice President for Nuclear Operations - Ft. Calhoun Station
Omaha Public Power District
P.O. Box 399, Hwy 75
North of Fort Calhoun
Fort Calhoun, NE 68023-0399

Reference: Your Purchase Order Number: 3565SUPPL#3, 53240, S011618, S016638, S022258
Foxboro Sales Order Number: 84N36017, 81N30237, 86N50528, 87N37033, 87N49735
Quantity:58
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

ATTN: Mgr. Nuclear Licensing & Industry Affairs
Omaha Public Power District
MS: FC-2-4 Adm. Bldg
Box 399, Highway 75
Fort Calhoun, NE 68023

Reference: Your Purchase Order Number: 3565SUPPL#3, 53240, S011618, S016638, S022258
Foxboro Sales Order Number: 84N36017, 81N30237, 86N50528, 87N37033, 87N49735
Quantity:58
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

ATTN: Director, Licensing
PECO Energy Company
965 Chesterbrook Blvd., 62A-1
Wayne, PA 19087-5691

Reference: Your Purchase Order Number: See Attached Sheet
Foxboro Sales Order Number: See Attached Sheet
Quantity:57
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Supervisor, Q.A. Engineering
Public Service Company Of Colorado
16805 Weld City Road 19 1/2
Platteville, CO 80651

Reference: Your Purchase Order Number: N3249, N4672, N4802
Foxboro Sales Order Number: 81N34333, 83N41493, 83N44551
Quantity:8
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

ATTN: Manager, Corporate Nuclear Quality Division
PECO Energy Company
965 Chesterbrook Blvd., 63C-1
Wayne, PA 19087-5691

Reference: Your Purchase Order Number: See Attached Sheet
Foxboro Sales Order Number: See Attached Sheet
Quantity:57
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Mr. Robert G. Byram
Senior V.P. -Generation and Chief Nuclear Officer
Pennsylvania Power and Light Company
2 North Ninth Street
Allentown, PA 18101

Reference: Your Purchase Order Number: 0-10655-1SUP#2, 2-17664-1
Foxboro Sales Order Number: 82N55213, 84N49990
Quantity:4
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Mr. A. Clegg Crawford
Vice President Electric Production
Public Service Company of Colorado
P.O. Box 840
Denver, CO 80201-0840

Reference: Your Purchase Order Number: N3249, N4672, N4802
Foxboro Sales Order Number: 81N34333, 83N41493, 84N44551
Quantity:8
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

I/C PM Analyst
Rochester Gas and Electric Corporation
R.E. Ginna Nuclear Power Plant
1503 Lake Road
Ontario, NY 14519

Reference: Your Purchase Order Number: See Attached Sheet
Foxboro Sales Order Number: See Attached Sheet
Quantity:31
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Operations Assessment
Rochester Gas and Electric Corporation
89 East Avenue
10th FLoor
Rochester, NY 14649

Reference: Your Purchase Order Number: See Attached Sheet
Foxboro Sales Order Number: See Attached Sheet
Quantity:31
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Ms. Jan Schori
General Manager
Sacramento Municipal Utility District
6201 S. Street
P.O. Box 15830
Sacramento, CA 95813

Reference: Your Purchase Order Number: GR88696
Foxboro Sales Order Number: 86N55260
Quantity:2
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Sierra Pacific Power Company
P.O. Box 249
Valmy, NV 89438

Reference: Your Purchase Order Number: 1556
Foxboro Sales Order Number: 81N55470
Quantity:21
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

ABB Electro-Mechanics
P.O. Box 750
New Britain, CT 06051

Reference: Your Purchase Order Number: 49851
Foxboro Sales Order Number: 85N38713
Quantity:2
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

ABB Electro-Mechanics
P.O. Box 750
New Britain, CT 06051

Reference: Your Purchase Order Number: 49851
Foxboro Sales Order Number: 85N38713
Quantity:2
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Argonnne National Laboratory
P.O. Box 2528
Idaho Falls, ID 83401

Reference: Your Purchase Order Number: 966-01
Foxboro Sales Order Number: 91F48299
Quantity:8
Model: N-2A0-L2C-R Contact output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Supervisor, D.D.C.
Arizona Public Service Company
P.O. Box 52034
Mail Station 6755
Phoenix, AZ 85072-2034

Reference: Your Purchase Order Number: See Attached Sheet
Foxboro Sales Order Number: See Attached Sheet
Quantity:204
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14,1999

Mr. Dale R. Leech
Mail Station 7965
Arizona Public Service Company
Palo Verde Nuclear Generating Station
5801 S. Wintersburg Road
Tonopah, AZ 85354-7529

Reference: Your Purchase Order Number: See Attached Sheet
Foxboro Sales Order Number: See Attached Sheet
Quantity:204
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Vice President, Operations
Entergy Operations Incorporated
Arkansas Nuclear One
1448 SR 333
Russellville, AR 78201

Reference: Your Purchase Order Number: 199380, 224711,41386, 41579, 48801, 12265SUPP No 1
Foxboro Sales Order Number: 84N52112,89N41503, 90F19458, 85N52599, 85N53047, 86N39216
Quantity:25
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Supervisor, Industry Events Analysis
Entergy Operations
Arkansas Nuclear One
Route 3, Box 137G
Russellville, AR 78201

Reference: Your Purchase Order Number: 12265 SUPP No 1, 199380, 224711, 41386, 41579, 48801
Foxboro Sales Order Number: 84N52112, 89N41503, 90F19458, 85N52599, 85N53047,86N39216
Quantity:25
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Supervisor, Engineering Databases
Entergy Operations
Arkansas Nuclear One
Route 3, Box 137G
Russellville, AR 72801

Reference: Your Purchase Order Number: 12265 SUPP No 1, 199380,224711, 41386, 41579, 48801
Foxboro Sales Order Number: 84N52112, 89N41503, 85N52599, 85N53047, 86N39216
Quantity:25
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Vice President - Nuclear Energy
Baltimore Gas and Electric Company
Calvert Cliffs Nuclear Plant
1650 Parkway
Lusby, MD 20657-4702

Reference: Your Purchase Order Number: 14100E, 33598-EX
Foxboro Sales Order Number: 82N36233, 83N37490
Quantity:6
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Mr. G. Douglas Whittier
Vice President Engineering and Licensing
Maine Yankee Atomic Power Company
329 Bath Road
Brunswick, ME 04011

Reference: Your Purchase Order Number: 37106-00
Foxboro Sales Order Number: 84N37676
Quantity:3
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Vice President Nuclear and Pilgrim Director
Boston Edison Company
RFD #1, Rocky Hill Road
Plymouth, MA 02360

Reference: Your Purchase Order Number: 34118, 34118-A, STR122258-001
Foxboro Sales Order Number: 81N43715, 82N43811, 92F09337
Quantity:4
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Executive Vice President - Energy Supply and Chief Nuclear Officer
Carolina Power and Light Company P.O. Box 1551
Raleigh, NC 27602

Reference: Your Purchase Order Number: B-25314CO1, B-26534, B-29740
Foxboro Sales Order Number: 85N35924, 85N30542, 85N45247
Quantity:8
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Acting Director, Nuclear Licensing & EQA
Combustion Engineering Incorporated
1000 Prospect Hill Road
Windsor, CT 06095

Reference: Your Purchase Order Number: 9874824-D9420
Foxboro Sales Order Number: 88N42441
Quantity:2
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Manager, Nuclear Regulatory Services
Commonwealth Edison Company
Executive Towers West III
140 Opus Place, Suite 900
Downers Grove, IL 60515

Reference: Your Purchase Order Number: See Attached Sheet
Foxboro Sales Order Number: See Attached Sheet
Quantity:94
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Mr. Kenneth L. Graesser
Site Vice President
Commonwealth Edison Company
4450 N. German Church Road
Byron, IL 61010

Reference: Your Purchase Order Number: 238231, 269199, 269207
Foxboro Sales Order Number: 81N41224, 82N56864, 82N56857
Quantity:41
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Mr. Timothy J. Tulon
Site Vice President Commonwealth Edison Company
RR #1
P.O. Box 84
Braceville, IL 60407

Reference: Your Purchase Order Number: 4G5875, 238232, 269201, 269208
Foxboro Sales Order Number: 91F34138,81N41223 82N56875, 82N56858
Quantity:43
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Mr. J.S. Perry
Site Vice President
Commonwealth Edison Company
Dresden Nuclear Power Station
6500 North Dresden Road
Morris, IL 60450-9765

Reference: Your Purchase Order Number: 30375, 303719, 303720, 303721, 303752, 303753
Foxboro Sales Order Number: 83N42614, 83N42622, 83N42621, 83N42609, 83N42615, 83N42165
Quantity:8
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

Mr. L. William Pearce

Site Vice President Quad Cities
Commonwealth Edison Company
Quad Cities Nuclear Power Station
22710-206th Avenue, North
Cordova, IL 61242

Reference: Your Purchase Order Number: 503006 REL XX60
Foxboro Sales Order Number: 93F16498
Quantity:2
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Mr. D.N. Morey
Vice President Farley Project
Southern Nuclear Operating Company, Inc.
P.O. Box 1295
Birmingham, AL 35201-1295

Reference: Your Purchase Order Number: 86510
Foxboro Sales Order Number: 89N47994
Quantity:2
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Mr. John K. Wood
Vice President, Nuclear - Davis-Besse
Toledo Edison Company
c/o Davis-Besse NPS
5501 N. State Route 2
Oak Harbor, OH 43449-9760

Reference: Your Purchase Order Number: C-601496-D90, Q012267, 046-Q-95926A-PN, 125-Q92388A-JA, Q009352ST, S-00240-D89,S-044515-D93
Foxboro Sales Order Number: 90F04692, 87N58993, 86N39928, 85N54492, 87N55474, 89N47605,93F04325
Quantity: 16
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Mr. Ted C. Feigenbaum
Executive Vice President and Chief Nuclear Officer
Northeast Utilities Service Company
c/o Mr. Terry L. Harpster
P.O. Box 128
Waterford, CT 06385

Reference: Your Purchase Order Number: See Attached Sheet
Foxboro Sales Order Number: See Attached Sheet
Quantity:646
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Mr. Bruce D. Kennyon
Chief Nuclear Officer- Northeast Nuclear
Northeast Nuclear Energy Company Millstone Energy Company
P.O. Box 128
Waterford, CT 06385

Reference: Your Purchase Order Number: 647221, 571832, 884365 REPL, 774781
Foxboro Sales Order Number: 83N51103, 81N58350, 93F21197,87N49944
Quantity:324
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Station Technical Bulletins Coordinator
Connecticut Yankee Atomic Power Company
362 Injnun Hollow Road
East Hampton, CT 06424-3099

Reference: Your Purchase Order Number: See Attached Sheet
Foxboro Sales Order Number: See Attached Sheet
Quantity:646
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Mgr. of Nuclear Operations Services
Northeast Nuclear Energy Services
105 Seldon Street
Berlin, CT 06037

Reference: Your Purchase Order Number: See Attached Sheet
Foxboro Sales Order Number: See Attached Sheet
Quantity:324
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Supervisor Procurement QA
Northeast Nuclear Energy Company
P.O. Box 270
Hartford, CT 06141-0270

Reference: Your Purchase Order Number: See Attached Sheet
Foxboro Sales Order Number: See Attached Sheet
Quantity:324
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Mr. John P. Stetz
Sr. Vice President - First Energy Nuclear Services
Centerior Energy Illuminating Company
76 Main Street
Akron, OH 44308

Reference: Your Purchase Order Number: C-601496-D90, Q012267, 046-Q-95926A-PN, 125-Q-92388A-JA, Q009352ST, S-00244-D89, S-044515-D93
Foxboro Sales Order Number: 90F04692, 87N58993, 86N39928, 85N54492, 87N55474, 89N47605,93F04325
Quantity:16
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Mr. Paul H. Kinkel
Vice President Nuclear Power
Consolidated Edison Company of New York
Broadway & Bleakley Avenue
Buchanan , NY 10511-1099

Reference: Your Purchase Order Number: 708668, 8696411
Foxboro Sales Order Number: 87N44544, 88N56893
Quantity:2
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

p>Mr. Robert A. Fenech
Sr. Vice President-Nuclear Fossil and Hydro Operations
Consumers Energy Company
212 W. Michigan Avenue
Jackson, MI 49201

Reference: Your Purchase Order Number: 0003-3649-CQ, 5006-5844-QA, 5009-0293-QA, 7220-J204AC, 7220-J-204-AC REV14, 9874824-9420 SUPPL 5
Foxboro Sales Order Number: 82N43112, 82N46764, 83N39766, 74N41545, 80N57780, 89N47024
Quantity: 181
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Vice President - Nuclear
Dairyland Power Cooperative
P.O. Box 817
La Crosse, WI 54601

Reference: Your Purchase Order Number: 0A8502673, A80406, 0A8503474
Foxboro Sales Order Number: 85N50217, 81N48223, 85N53601
Quantity:5
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Mr. Douglas R. Gipson
Sr. Vice President Nuclear Generation
Detroit Edison Company
6400 North Dixie Highway
Newport, MI 48166

Reference: Your Purchase Order Number: 1A-53418
Foxboro Sales Order Number: 84N37161, 81N35979
Quantity:8
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Supervisor Material Enqineerina
Detroit Edison - Fermi 2
ATTN: Engineering Tracking System (ETS)
6400 North Dixie Highway
Newport, MI 48166'

Reference: Your Purchase Order Number: 1A-53418
Foxboro Sales Order Number: 84N37161, 81N35979
Quantity:8
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Mr. J.E. Cross
President - Generation Group and Chief Nuclear Officer
Duquesne Light Company
P.O. Box 4
Shippingport, PA 15077

Reference: Your Purchase Order Number: D036060
Foxboro Sales Order Number: 87N34830
Quantity:18
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Mr. Joseph J. Hagan
Vice President Operations, Grand Gulf
Entergy Operations, Inc. P.O. Box 756
Port Gibson, MS 39150

Reference: Your Purchase Order Number: 205-XG707, 9645-J-318.1, 9645-J-318.1 REV4, M70001
Foxboro Sales Order Number: 81N39760, 82N56478, 81N53379
Quantity:5
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Mr. John R. McGaha, Jr.
Vice President
Entergy Operations, Inc.
P.O. Box 220
St. Francisville, LA 70775

Reference: Your Purchase Order Number: 205-AH928
Foxboro Sales Order Number: 80N49909
Quantity:4
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Mr. T.F. Plunkett
President, Nuclear Division
Florida Power and Light Company
P.O. Box 14000
Juno Beach, FL 33408-0420

Reference: Your Purchase Order Number: See Attached Sheet
Foxboro Sales Order Number: See Attached Sheet
Quantity:24
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

Manager of Quality Assurance Services
Florida Power & Light Company
P.O. Box 14000
Juno Beach, FL 33400-0420

Reference: Your Purchase Order Number: See Attached Sheet
Foxboro Sales Order Number: See Attached Sheet
Quantity:24
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Site Purchasing Supervisor
Florida Power & Light Company
Turkey Point Nuclear Plant
P.O. Box 3088
Florida City, FL 33034

Reference: Your Purchase Order Number: See Attached Sheet
Foxboro Sales Order Number: See Attached Sheet
Quantity:24
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Mr. Roy A. Anderson
Sr. Vice President, Energy Supply
Florida Power Corporation
P.O. Box 14042
St. Petersburg, FL 33733

Reference: Your Purchase Order Number: See Attached Sheet
Foxboro Sales Order Number: See Attached Sheet
Quantity: 173
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Manager of Nuclear I/C Engineering
Florida Power Corporation
P.O. Box 14042
St. Petersburg, FL 33733

Reference: Your Purchase Order Number: See Attached Sheet
Foxboro Sales Order Number: See Attached Sheet
Quantity: 173
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of.a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Mr. Michael B. Roche
Vice President and Nuclear Director
GPLI Nuclear Corp.
Oyster Creek Generating Station
P.O. Box 388
Forked River, NJ 08731

Reference: Your Purchase Order Number: 0420364, OP-026940, PP-035001, PP-058412, PP-066586, 71318DN
Foxboro Sales Order Number: 93F14995, 85N47998, 86N36864, 87N55890, 88N42654, 81N46871
Quantity:41
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Vendor Document Control Engineer
GPU Nuclear Corp.
Oyster Creek Nuclear Station, Trailer 300
P.O. Box 388
Forked River, NJ 08731

Reference: Your Purchase Order Number: 0420364, OP-026940, PP-035001, PP-058412, PP-066586, 71318DN
Foxboro Sales Order Number: 93F14995, 85N47998, 86N36864, 87N55890, 88N42654, 81N46871
Quantity:41
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Mr. J.D. Woodward
Executive Vice President Nuclear Operations
Southern Nuclear Operating Company, Inc.
P.O. Box 1295
Birmingham, AL 35201

Reference: Your Purchase Order Number: G16024, PEHA-48 C.O.7,PCG2-5658, PAV-26028
Foxboro Sales Order Number: 81N58923, 82N42840,82N42839, 83N44967, 85N39445
Quantity:1
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Mr. James W. Langenbach
Vice President and Director TMI
GPU Nuclear Corporation
P.O. Box 480
Middletown, PA 17057

Reference: Your Purchase Order Number: See Attached Sheet
Foxboro Sales Order Number: See Attached Sheet
Quantity: 123
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays,- no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Mr. Russell W. Krieger
Vice President - Nuclear Generation
Southern California Edison Company
P.O. Box 128
San Clemente, CA 92674

Reference: Your Purchase Order Number: See Attached Sheet
Foxboro Sales Order Number: See Attached Sheet
Quantity:358
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Operating Experience Manager
Tessessee Valley Authority
1101 Market Street
BR 4X
Chattanooga, TN 37402

Reference: Your Purchase Order Number: See Attached Sheet
Foxboro Sales Order Number: See Attached Sheet
Quantity:278
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Mr. D.F. Schnell
Sr. Vice President - Nuclear
Union Electric Company
P.O. Box 149
St. Louis, MO 63166

Reference: Your Purchase Order Number: 090660, 096775, 10466-J-110-2, 10466-J-110-2REV16, 10466-SPJ-110-2, 84730,93624
Foxboro Sales Order Number: 91F15951, 89F04103, 76N56503, 82N40657, 81N43335, 87N40318, 86N41913
Quantity:54
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Mr. J.V. Bemis
Vice President, Nuclear Operations
Washington Public Power Supply System
MD PE20
P.O. Box 968
Richland, WA 99352

Reference: Your Purchase Order Number: 64396-N19733
Foxboro Sales Order Number: 79N57395
Quantity:76
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Mr. Michael B. Sellman
Chief Nuclear officer
Wisconsin Electric Power Company
231 W. Michigan Street
Milwaukee, WI 53201

Reference: Your Purchase Order Number: A65127-S, B29856-S, B-52578-P, P0136831 000
Foxboro Sales Order Number: 8ON62550, 83N39356, 84N36162, 89N34395
Quantity:72
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Mr. Clark Steinhardt
Sr. Vice President - Nuclear Power
Wisconsin Public Service Corporation
P.O. Box 19002
Green Bay, WI 54307-9002

Reference: Your Purchase Order Number: 02736, 08996, 119368, 54116
Foxboro Sales Order Number: 89N33914, 85N51376, 92F23100, 83N42310
Quantity:13
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Mr. Andrew Kadak
President
Yankee Atomic Electric Company
580 Main Street
Bolton, MA 01740-1398

Reference: Your Purchase Order Number: 103265, 103857
Foxboro Sales Order Number: 84N30755, 84N 41295
Quantity:10
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


FOXBORO

The Foxboro Company
Foxboro, MA 02035-2099
United States of America
Telephone +1 508 543 8750
Facsimile +1 508 549 6750
Internet http://iom.invensys.com/UK/Pages/Foxboro.aspx/ [EXIT]

July 14, 1999

Mr. Otto L. Maynard
President and Chief Executive Officer
Wolf Creek Nuclear Operating Corporation
P.O. Box 411
Burlington, KS 66839

Reference: Your Purchase Order Number: 10466-J-110-1, 10466-J-110-1 (Q)
REV16, 10466-SPJ-1101, 519500
Foxboro Sales Order Number: 76N56505, 82N40656, 81N43334, 87N43104
Quantity:
Model: N-2A0-L2C-R Contact Output Isolator

Dear Customer,

In compliance with 10CFR Part 21 this letter is to inform you of a potential failure with N-2A0-L2C-R Contact Output Isolator cards purchased from The Foxboro Company as referenced above. The subject Contact Isolator cards may contain N0152CK or C0147SS relays supplied by Potter & Brumfield which were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path.

Analysis performed on two returned relays showed that they were in operation for 8 years (displaying date codes of 9110 & 9112) before a resistive shunt path developed across the Normally Open and/or the open Normally Closed contact. Further analysis performed by the supplier of.the relay confirmed the resistive shunt path was caused by the existence of tin whisker growth between the contact support arms. To date, this is the first confirmed instance of this failure mode on these relays.

The Foxboro Company has two sources of these relays qualified for use. However, this failure mode is limited to those relays supplied by Potter & Brumfield which were manufactured between 1977 and 1993 with tin plated contact support arms. The Foxboro Company presently has another source, Communications Instruments Inc (formerly SIGMA) qualified for use. Due to the different construction techniques utilized on the CII relays, no concern of tin whisker growth exists on those relays.

SIEBE

A Siebe Group Company


*** END OF DOCUMENT ***
Page Last Reviewed/Updated Thursday, March 29, 2012