Demystification of Arc-Fault Circuit Interrupters: Part 2: Technology and Applications

Residential Fires of Electrical origin have been a major concern for a long time. A fire can be initiated by excessive current (due to an overload or a short circuit) or arcing current. Therefore, both Canadian Electrical Code (CE Code) part 1 and the National Electrical Code (NEC) require the installation of overcurrent protection devices (OCPDs) to detect and clear excessive current. Conversely, arcing current is too low for OCPDs to detect. It could take an electric arc minutes, days, weeks, months, or even years to initiate a fire. Therefore, a new solution was required for detecting slowly developing arcs. Thus, arc-fault circuit interrupters (AFCIs) were born. AFCIs are capable of detecting an arcing condition (while it is still developing) and deenergizing the circuit before the arcing circuit ignites.