In this video, Scott Caron, master electrician for Ask This Old House, wires an old house with new smoke and carbon monoxide detectors.
Steps for Installing Smoke & Carbon Monoxide Detectors
- Mark the location of each smoke detector on the ceiling.
- Use a drill and long, stiff wire to bore a small-diameter hole through the ceiling and into the attic.
- Go into the attic and check for obstructions around the small holes. If necessary, use a circular saw to cut open the attic floor.
- At each smoke detector location, use a drill and a 4-inch-diameter hole saw with dust shield to cut a hole through the ceiling for a round old-work electrical box.
- Run nonmetallic electrical cable from an existing outlet in the attic to each of the smoke detector locations.
- Cut the cable and pull it through an old-work electrical box. Push the box into the ceiling hole and tighten the screws to lock the box to the ceiling. Repeat for each ceiling hole.
- Screw the smoke detector’s mounting plate to the box, then make the wire connections: black to black, white to white, red to orange.
- Gently tuck the wires into the box, then twist and lock the smoke detector onto the mounting plate.
- Install a combination smoke and carbon monoxide detector on each level of the home and within 10 feet of the bedrooms.
- Pull a new electrical cable down from the attic into the basement.
- In the basement, install a standard hardwired combination smoke and carbon monoxide detector, and a two-piece wireless smoke and carbon monoxide detector. Mount the battery-powered wireless half of the detector on the first-floor ceiling.
- Make the final wire connections in the attic, then test each detector to make sure all of them are operating properly.