Arcfaults

Arcfaults are electrical discharges that occur when an electric current jumps through air or other insulating medium between conductive paths, creating a plasma channel. Arcs produce high temperatures, light, noise, and irregular current flow, and can cause heating, equipment damage, and fires. In power systems and electrical installations, arcs can occur within cables, switchgear, or connections when insulation is damaged, conductors are loose, or moisture or contaminants are present.

Arcfaults are typically categorized as series arc faults or parallel (shunt) arc faults. A series arc occurs along a single conductor and raises impedance, while a parallel arc forms between conductors or between a conductor and ground. Arc faults emit distinctive high-frequency transients and noisy current spectra, often with rapid dV/dt and fluctuating amplitudes, which differentiates them from normal load currents.

Protection against arcfaults relies on arc fault circuit interrupters (AFCIs) and, where ground faults are involved, combination devices that may integrate with GFCIs. AFCIs monitor current signatures to detect the arcing pattern and trip the circuit before an arc ignites surrounding material. In many jurisdictions, AFCI protection is required for new residential circuits by electrical codes such as the NEC. Preventive measures include good wiring practices, properly sized and routed cables, secure terminations, moisture control, and routine inspection of cords and outlets.

Arcfault research continues to improve detection algorithms, including spectral analysis and waveform recognition, to reduce nuisance tripping while maintaining safety. Arcfaults are a major fire hazard in electrical installations, distinct from other faults like short circuits or overloads, and are a primary focus of electrical safety engineering.