Breakers with AF suffix provide standard thermal/magnetic protection, PLUS protection against heat damage caused by parallel AND SERIES arcing in the circuit. A series arc occurs when electricity jumps the gap between the strands within the same wire. An example of what may cause a series arc is when an extension cord is damaged because it has been smashed between furniture and the wall, cracking the insulation and exposing strands within one wire. Arcing may occur strand to strand. Breakers designed to protect against parallel and series arcs are called Combination Arc-Fault Circuit Breakers
