How to install interconnected smoke alarms

Updated February 21, 2017

Interconnecting smoke alarms allow the sensor in one alarm to trigger the audible and visual warning system in the other alarms. They are useful in multi-room dwellings where, if a fire were to start in an unoccupied part of the home, the occupants in another part of the home are warned of the danger. There are recommended locations for smoke alarms and also specific installation, operation and testing requirements.

Determine the locations for your interconnected alarms. Locate the first alarm in the immediate vicinity of bedrooms. Locate additional alarms on each level. Stairways are also good locations because they act as chimneys. Mount the alarms on walls or ceilings. Ceiling mountings should be at least 4 inches from the side wall. Wall mountings should be a minimum of 4 inches and a maximum of 12 inches below the ceiling.

Wire the alarm circuit. The alarm wiring should run from an un-switched 120V power source to junction boxes. Disconnect the power, and connect the black and white wires from the power source to the black and white wire on the quick connector on the first alarm. Connect the black and white wires from the first alarm's quick connector to the black and white wire on the second connector and so on. Connect a third orange, red or yellow wire between alarms. There is no third wire from the power source. Many areas will require an electrician to make the final connections.

Affix the alarms. Attach the mounting ring to the ceiling. Pull the quick connector through the ring, and plug it into the alarm. Rotate the alarm onto the mounting ring clockwise until it ratchets into place.

Pull the protruding battery tab out to connect the battery, and test the alarms by pressing on the "Test" button for at least five seconds.

Reestablish AC power.


Most alarms can only be interconnected to other alarms of the same make.

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About the Author

Patrick Nelson has been a professional writer since 1992. He was editor and publisher of the music industry trade publication "Producer Report" and has written for a number of technology blogs. Nelson studied design at Hornsey Art School.