Which device is designed to protect against arc faults across the entire circuit?

• A. GFCI
• B. AFCI
• C. Dual-function
• D. Ground-fault protector

Answer: (B)

Arc fault protection across an entire circuit is provided by arc-fault circuit interrupters. These devices monitor the electrical waveform for the distinctive signatures that occur when arcing happens in wiring or devices, such as rapid, erratic current spikes. When such arcing is detected, the AFCI trips and opens the circuit, helping prevent electrical fires. This protection typically covers the whole branch circuit when the AFCI is a circuit breaker at the panel or a combination device installed to guard the entire run.

GFCIs, by contrast, protect people from shock by sensing imbalances between hot and neutral and are not designed to detect arcing. A dual-function device combines AFCI and GFCI protections, offering both arc-fault and ground-fault protection, but for arc faults across the entire circuit, AFCI specifically is the device designed for that role.