Quote:
Originally Posted by Bill_B
I do not think the thermal characteristics of the insulation is (or should be) a factor in determining the size of the circuit protector.
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The circuit breaker is sized to protect the wiring. If the wiring can has a higher ampacity, a larger circuit breaker may be used.
Ampacity is calculated based on the temperature rise of the wire among other things. If a higher quality insulation is used which has a higher temperature rating, the wire can handle higher current. Therefore, a larger circuit breaker may be used.
FIRST must be conservative when choosing wire sizes that teams must use, but that's why a smaller wire could be used based on the insulation.