Smoke Detectors on AFCI Protected Circuit?

Let’s review the 2008 NEC

Dwelling Unit Circuits. All 15A or 20A, 120V branch circuits in dwelling units supplying outlets in family rooms, dining rooms, living rooms, parlors, libraries, dens, bedrooms, sunrooms, recreation rooms, closets, hallways, or similar rooms or areas must be protected by a listed AFCI device of the combination type [210.12(B)].

The 120V circuit limitation means AFCI protection isn’t required for equipment rated 230V, such as a baseboard heater or room air conditioner. For more information, visit www.MikeHolt.com, click on the “Search” link, and search for “AFCI.”

Smoke alarms connected to a 15A or 20A circuit of a dwelling unit must be AFCI protected if the smoke alarm is located in one of the areas specified In 210.12(B). The exemption from AFCI protection for the “fire alarm circuit” contained in 760.41(B) and 760.121(B) doesn’t apply to the single-or 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-or multiple-station smoke alarms, fire alarm systems are managed by a fire alarm control panel.

Note: An arc-fault circuit interrupter is a device intended to de-energize the circuit when it detects the current waveform characteristics unique to an arcing fault [210.12(A)].

Mike Holt’s Comment: The National Fire Marshals Association supports the NEC requirement that circuits for smoke detectors be AFCI protected.

You might find the following news article from The Buffalo News (New York) http://www.buffalonews.com/437/story/596807.html to be of some interest.

A faulty smoke detector sparked a fire that caused $175,000 damage to a Clarence home at about 4:45 p.m. Tuesday, Amherst Fire Control said.

The fire at 8895 County Road started shortly before 4:45 p. m. and was noted by a volunteer firefighter passing the scene.

Clarence Center firefighters battled the blaze with crews from Clarence, Getzville and East Amherst. Clarence Center Chief David Case said the fire was caused by the smoke detector in the living room ceiling. The blaze caused extensive fire, heat and smoke damage throughout the 1-1/2-story wood frame house.

No one was home at the time of the blaze. The American Red Cross was assisting the family, which was displaced by the fire.