United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 81-06: Failure of ITE Model K-600 Circuit Breaker

                                                            SSINS No.: 6835 
                                                            Accession No.: 
                                                            8011040269     
                                                            IN 81-06       

                                UNITED STATES
                        NUCLEAR REGULATORY COMMISSION
                    OFFICE OF INSPECTION AND ENFORCEMENT
                           WASHINGTON, D.C. 20555
                                     
                               March 11, 1981

Information Notice No. 81-06: FAILURE OF ITE MODEL K-600 CIRCUIT BREAKER 

Purpose: 

The purpose of this information notice is to provide early notification of a 
matter that could adversely affect the safety of nuclear power plants. 
Toward this end, this information notice alerts holders of operating 
licenses and construction permits of a possibly generic deficiency involving 
Model K-600 circuit breakers manufactured by ITE. 

Description of Circumstance: 

By letter dated February 20, 1981, the Sacramento Municipal Utility District
informed us that, while performing preventive maintenance on electrical 
circuit breakers at its Rancho Seco facility, an ITE Model K-600 breaker was
observed not to trip. An investigation revealed that a tripping coil wire 
had slipped out of its terminal. Further examinations revealed that the coil 
wire size was AWG 20, whereas the mating lug was sized for AWG 16-14 wire. A 
check of other ITE electrical breakers indicated that the problem may be 
generic. Subsequent to the letter, the Sacramento Municipal Utility District 
informed us orally that ITE Model K-1600 breakers have the same deficiency 
and that Model K-3000 breakers may be similarly affected. 

The information provided by the Sacramento Municipal Utility District is 
preliminary and will be followed by a complete report. Consequently, we have
not yet evaluated the safety significance of this event. Nevertheless, the 
information herein is being provided as an early notification of a possibly 
significant event. Although no specific action or response is requested at 
this time, recipients should review the information for possible 
applicability to their facilities. If NRC evaluations so indicate, further 
licensee actions may be requested. 

If you have any question regarding the information contained herein, please 
contact the Director of the appropriate NRC Regional Office. 

Attachment:
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