Which circuits are covered by the AFCI requirement?

• A. 120-volt, single-phase, 15- and 20-ampere branch circuits
• B. 240-volt circuits
• C. 120-volt, 30-amp circuits
• D. All circuits, regardless of voltage or phase

Answer: (A)

AFCI protection is designed to stop fires by detecting dangerous arcing in residential branch circuits. The circuits specifically covered are the 120-volt, single-phase branch circuits that are rated for 15 or 20 amperes. These are the typical circuits that supply most outlets and lighting in homes, and AFCI devices—whether built into breakers or receptacles—are sized for 15/20 A. 240-volt circuits are not part of this basic AFCI requirement, and a 120-volt circuit rated at 30 amps falls outside the common AFCI coverage because standard AFCI devices are designed for 15/20 A. Therefore, the correct choice is the 120-volt, single-phase, 15- and 20-ampere branch circuits.