I think that some here may be rushing to an incorrect conclusion... that being the temperatures that have been mentioned are going to cause or create some catastrophic condition within the panel enclosure.
Take a close look at the temperature ratings of conductors at the top of Table 310.16. You will see that the temperatures for the conductors are higher than most usually comprehend. These temps are also relative to some equipment.
Also, to mention is that the manufacturers have already tested the existing Arc Fault CBs with the existing electronics at the temps created within the Arc Fault CB and know that the standard temps are elevated.
If one was to load a 20 amp circuit up to its full limit, the temperature of a standard circuit breaker would be well over 125F, I cannot remember the exact temperature. There is a formula to come to a close number and I cannot find it. Circuit breakers under load get warm - hot and a lot of people think something may be wrong...not always.
Last, the manufacturers have all redesigned the electronics in their newer Arc Fault CBs and the operating temperature will be reduced. I have not heard yet of one failure of Arc Fault CBs due to temperature issues.
I would not call the fire department just yet
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