Arc Fault Circuit Interrupter (AFCI) Protection

By Mike Holt
Arc fault circuit interrupter protection requirements for 15A and 20A, 120V dwelling unit circuits were expanded again. Section 210.12(B) now reads as follows:
"All 15A or 20A, 120V branch circuits that supply outlets in dwelling unit family rooms, dining rooms, living rooms, parlors, libraries, dens, bedrooms, sunrooms, recreation rooms, closets, hallways, or similar areas shall be protected by a listed AFCI device of the combination type."
The 120V circuit limitation means AFCI protection isn't required for equipment rated 230V, such as baseboard heaters or room air conditioners. In addition, AFCI protection is not required in rooms or areas protected by GFCIs. Though not required by the Code, both AFCI and GFCI protection can be provided for the same branch circuits or receptacle outlets, as the different protection technologies are compatible.
In addition, a new Fine Print Note clarified dwelling unit AFCI protection requirements of fire alarm circuits, and the rules on locating the AFCI device were rewritten to relax the restrictions.
"FPN No. 3: See 760.41 and 760.121 for power-supply requirements for fire alarm systems."
Smoke alarms connected to a 15A or 20A circuit must be AFCI-protected if the smoke alarm is located in the bedroom of a dwelling unit. The exemption from AFCI protection for the "fire alarm circuit" contained in 760.41 and 760.121 doesn't apply to the single and multiple station smoke alarm circuit typically installed in dwelling unit bedroom areas. This is because a smoke alarm circuit isn't a fire alarm circuit as defined in NFPA 72, National Fire Alarm Code. Unlike single and multiple station smoke alarms, fire alarm systems are managed by a fire alarm control panel.
"Exception No. 1: The AFCI protection device can be located at the first outlet if the circuit conductors are installed in RMC, IMC, EMT or steel Type AC, and the AFCI device is contained in a metal outlet or junction box."
Type MC cable without a bare aluminum grounding/bonding conductor does not fall within the scope of this exception because the armor cable is thinner than that of Type AC cable.
"Exception No. 2: AFCI protection can be omitted for branch-circuit wiring to a fire alarm system in accordance with 760.41(B) and 760.121(B), if the circuit conductors are installed in RMC, IMC, EMT, or steel armored Type AC cable."
This new Fine Print Note alerts Code users to the fact that AFCI protection is not required for the "fire alarm circuit," but caution must be exercised because 760.41 and 760.21 don't apply to the single and multiple station smoke alarm circuit typically installed in dwelling unit bedroom areas. This is because a smoke alarm circuit isn't a fire alarm circuit as defined by NFPA 72, National Fire Alarm Code. Unlike single and multiple station smoke alarms (smoke detectors), fire alarm systems are managed by a fire alarm control panel, which qualifies it as a fire alarm system.