Installing Hardwired Smoke Detectors

Intro

Hardwired smoke detectors with battery backup are required in some places. They are wired in a series so when one alarm sounds, all sound. Running the cable is the hardest part of the job -- the time required depends on the layout of your home. In addition, you'll need to tie in to a single source of power.

Checklist

Time
About 5 hours to run cable and install three detectors

Tools
Voltage tester, drill, 1/2-inch bit, drywall saw, fish tape, screwdriver, strippers, long-nose pliers, lineman's pliers

Skills
Installing boxes; running cable into boxes; stripping, splicing, and connecting wires to terminals

Materials
Smoke detectors, boxes, 14/2 and 14/3 cable, electrician's tape, wire nuts

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Wiring Smoke Detectors in a Series

Use 14/2 cable to feed the first detector in the series and 14/3 cable for subsequent units. The yellow lead from each detector interconnects the system so all detectors sound at once.

Step 1

For each detector, cut a hole for a standard 4-inch octagon or single-gang box. Run 14/2 cable to the first detector in the series and 14/3 cable to the others. Install the boxes.

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Step 2

Align the slots of the mounting plate and attach the plate to the box. Gently pull the wires through the plate. After connecting the first box in the series, connect wires as shown.

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Step 3

After securing the wire nuts with electrician's tape, gently push the wires into each box. Install the detectors, activate the backup batteries, and connect to the power source.

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For Extra Protection: Install a plug-in carbon monoxide alarm

Carbon monoxide, an odorless, colorless, poisonous gas, results from combustion. Faulty venting for appliances, wood or charcoal burners, or the incursion of auto exhaust can put your household at risk. Plug-in units like this have battery backup.

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