United States Nuclear Regulatory Commission - Protecting People and the Environment


Licensee/Facility:                     Notification:

Southern California Edison & San       MR Number: 4-95-0035
Diego Gas & Electric Co.               Date: 03/17/95
San Onofre 2                           Telephone Call from Resident       
San Clemente,California              
Dockets: 50-361

Reportable Event Number: N/A


On March 15, 1995, the licensee discovered that the wrong size lugs were 
connected to wires for incoming and outgoing DC control power to various 
Unit 2 safety-related circuit breakers.  The affected circuit breakers   
were located in the Train B Class 1E 4.16 KV switchgear and in the       
Train B Class 1E 480 volt switchgear.  The licensee made the discovery   
while the switchgear was deenergized during the Unit 2 current refueling 
The lugs were color-coded yellow with three black stripes, which should  
have been 14/16-gauge, per the vendor catalogue.  The lugs were actually 
10/12-gauge and were installed on 14-gauge wire.  Consequently, the lugs 
were too large for the application and could separate from the wire more 
easily than a properly sized lug.                                        
The lugs were manufactured by Amp Incorporated, of Harrisburg, PA, and   
the switchgear was provided by ITE Imperial, now owned by ABB/Combustion 
Engineering.  The lugs are a part of the switchgear and have been in     
place since construction in the early 1980s.  The licensee contacted Amp,
Incorporated and the company is researching color coding requirements for
lug size during the time in which the switchgear was provided.  The      
licensee is evaluating the reportability of this occurrence under 10 CFR 
Part 21.                                                                 
The licensee plans to replace the improper lugs prior to declaring the   
switchgear operable.  The licensee also plans to inspect the other       
Class 1E 4.16 KV and 480 Volt switchgear (Unit 2 Train A and both trains 
in Unit 3) at the next opportunity.  The inspection requires removing    
wires from terminals and reading the inscribed lug size.  The inspection 
cannot be accomplished with DC control power energized.                  
The licensee's preliminary risk evaluation of having lugs too large was  
that the risk was small, as there was no evidence of separation of the   
wires from the lugs.  The licensee found that most lugs were tightly     
connected to the wires.  Previous work to replace DC circuit breakers had
not identified any loose connections.  In addition, a control room alarm 
will occur to indicate a problem with DC control power if a lug separated
from a wire.                                                             
San Onofre Unit 2 is currently in Mode 6 during a refueling outage, and  
Unit 3 is operating at full power.                                       

REGION IV  MORNING REPORT     PAGE  2                    MARCH 17, 1995
MR Number: 4-95-0035 (cont.)

Regional Action:

The resident inspectors will monitor the licensee's activities to inspect
and replace the lugs.                                                    

Contact:  H. Wong                    (510)975-0296
          J. Russell                 (714)492-2641

Page Last Reviewed/Updated Monday, January 27, 2020