A. Art Laurenson, a Providence, R.I., firefighter and assistant deputy state fire marshal, responds: To be sure you are complying with local regulations, contact your local electrical inspector and the local fire department. For new construction, BOCA and NFPA 70 (the National Electrical Code) both require hard-wired, interconnected devices with battery back-up.
Residential smoke alarms should be wired on a dedicated circuit. It’s a good idea to have at least one light or receptacle-on the same circuit, to alert the homeowners in case the circuit breaker ever trips. Interconnected alarms are usually wired in a daisy chain, using 14-3 or 12-3 cable. The third conductor is the communication wire.
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