arcfault

An arcfault is an electrical fault characterized by the formation of an electric arc between conductors or between a conductor and an earthed surface. The arc conducts electricity and concentrates energy at the fault site, producing heat, light, and potentially plasma. Arcing faults are a common cause of electrical fires and can occur in damaged, stressed, or poorly installed wiring. The term arcfault is distinct from arc flash, which refers to the energy release and hazards that accompany arcing.

Causes include degraded insulation, loose or corroded connections, damaged cables, and pinched or stressed wiring due to movement or aging. Arcs can occur in series faults (between two points on a single conductor) or parallel faults (between conductors and ground or neutral). Arcing heats the conductors rapidly and can degrade insulation further, creating a fire risk.

Protection and detection: Arc fault circuit interrupters (AFCIs) detect characteristic signatures of arcing in the current or voltage waveform and interrupt the circuit to prevent sustained arcing. Some devices combine AFCI with a ground-fault interrupter (GFCI). AFCIs are commonly installed on residential branch circuits to reduce fire risk and are often required by electrical codes in new construction.

Arcfaults are typically discussed alongside related concepts such as arc flash and short circuit. Proper installation, insulation maintenance, and periodic inspection reduce arcing risk; when replacing wiring or fixtures, using properly rated conductors and connectors minimizes arcing potential.