AFCI do add a measure of protection from series arcs and some parallel arcs both of which tend to be less than 5 amps of current which no regular breaker would trip
i had thought it predicated on the arc
signature more than an actual
threshold~S~
Sparky You are correct. My point about current magnitude is related to tripping of a normal breaker. Series arcs in low voltage circuits don't draw enough current to make a regular breaker trip and allows that series arc to perpetuate and possibly ignite adjacent combustibles. An arc fault breaker recognizes the wave form or electrical characteristics of an arc and opens the circuit. The common misconception was that a regular circuit breaker should protect us from all the hazards. parallel arcs are usually revealed as a ground fault, phase to neutral or phase to phase fault. AFCI Breakers also are designed to detect ground faults and trip around the 30 ma level. These are not life safety GFCI which trip at 6 ma and should resist small leakage currents like we might see in a heating element.
