Could an AFCI feel warmer than other breakers in the same panel?
An AFCI breaker may feel warmer to the touch than a non-AFCI circuit breaker. This is due to the heat generated from the power supply for the electronics. Siemens AFCI breakers tested in an average ambient temperature of 23° C (73° F) operated at an average temperature of 38° C (100° F.) This is well within the UL Standard 489 Section 220.127.116.11.6 which states - Temperature rises on handles, knobs, and other surfaces subject to user contact during normal operation shall not exceed 60°C (140°F) on nonmetallic surfaces. It is warm enough to detect with the hand, but this heat does not impact the operation of the AFCI.