Arc-Fault Circuit Interrupter (AFCI) protection is intended to prevent fires caused by which condition?

• A. Ground faults
• B. Short circuits
• C. Arcing faults
• D. Overload faults

Answer: (C)

Fires caused by arcing faults are what AFCIs are designed to prevent. An arc in wiring—such as at a loose connection or damaged insulation—produces a hot, intermittent current that can ignite surrounding materials. AFCIs monitor the electrical waveform for the distinctive patterns of arcing, including both series arcs (in a single conductor) and parallel arcs (between conductors), and trip to stop the current before ignition can occur. Ground faults, which cause shock and are handled by GFCIs, involve leakage to ground and aren’t the fire scenario AFCIs protect against. Short circuits and overload faults involve large currents or overheating addressed by other protection, not the arcing signature that AFCIs specifically detect. So the condition AFCIs target is arcing faults.