What is the temperature rating of the lugs on circuit breakers?
Issue:
Are breakers rated for 90C wire?
Product Line and Environment:
All Circuit Breakers
Resolution:
The wire temperature rating allowed for use in circuit breakers lugs is 75°C. While it is acceptable to use 90°C wire, that 90°C wire must be sized as if it is 75°C wire. This is according to the UL standard for circuit breakers, which is summarized as follows:
(1) Breakers rated 125 A or less must be marked for use with 60°C, 60/75°C, or 75°C only wire.
(2) For breakers rated more than 125 A, the proper wire temperature rating is 75°C and the marking is optional.
(3) Wire with a higher temperature rating can be used (e.g. 90°C), but the ampacity of the wire must be based on the wire temperature marked on the breaker.
Therefore, as marked on the breaker, the wire must be sized as 75°C wire. Even when using 90°C wire, the wire must be sized as if it is 75°C wire.
Are breakers rated for 90C wire?
Product Line and Environment:
All Circuit Breakers
Resolution:
The wire temperature rating allowed for use in circuit breakers lugs is 75°C. While it is acceptable to use 90°C wire, that 90°C wire must be sized as if it is 75°C wire. This is according to the UL standard for circuit breakers, which is summarized as follows:
(1) Breakers rated 125 A or less must be marked for use with 60°C, 60/75°C, or 75°C only wire.
(2) For breakers rated more than 125 A, the proper wire temperature rating is 75°C and the marking is optional.
(3) Wire with a higher temperature rating can be used (e.g. 90°C), but the ampacity of the wire must be based on the wire temperature marked on the breaker.
Therefore, as marked on the breaker, the wire must be sized as 75°C wire. Even when using 90°C wire, the wire must be sized as if it is 75°C wire.
Released for: Schneider Electric Canada
