Circuit breakers are designed
with the use of 90C conductors as a "heat sink".
The conductors will help to take some of the heat away from the circuit breaker itself onto the conductor.
Pierre,
I am respectfully curious now.
(1) Does UL test circuit breakers for thermal trip levels
with the internal heat being dissipated somewhat by the conductors?
or
(2) Does the conductor dissipate its own heat (outside of the test) ?
I have worked with Load Centers which were heated by ambient temp
such that the breakers tripped at 15A, instead of 20A load. Understandable.
The internal bi-metalic heater does not know where the temp comes from.
In any case,
I don't see how the temp rating of the insulation enters into the picture.
The CB terminals are rated at 75 degrees which limits the wire temp rating.
Another question, does the 60 degree insulation (old TW) dissapate more heat
than the 90 degree insulation (new THHN) ?
:smile: I can't always answer my own questions.