How to Repair a Hard-Wired Smoke Detector

Trip the circuit breaker at the fuse box to discontinue (temporarily) the electric power going to the room where the smoke detector is located.

Place a ladder beneath the smoke detector. Remove the screws from around the smoke detector's mounting plate with a Phillips screwdriver. Pull the mounting plate off the ceiling.

Pull the wires out of the hole in the ceiling. Twist the screw-nut connectors off the twisted pairs of wires with your fingers. Separate the wires from each other using your fingers.

Aim a flashlight into the hole in the ceiling. Tighten the screw on the electrical junction box that is inside the ceiling with the Phillips screwdriver.

Place an end of the included plastic straw on the nozzle of the electrical lubricant spray can. Shake the can for five seconds. Spray a two-second burst onto each screw.

Scrape the ends of the wires coming out of the hole with the blade of a utility knife. Repeat this procedure with the wires attached to the smoke detector.

Wind the exposed end of the black wire from the smoke detector around the exposed end of the black wire from the hole in the wall. Repeat this procedure with the white wires from the detector and from the hole. Repeat this procedure with the copper-colored wires from the detector and from the hole.

Repeat this procedure with the yellow wires from the detector and from the hole; if there is no yellow wire in the hole (connecting the detector to another detector elsewhere), ignore doing this step and add a piece of electrical tape around the already-taped end of the yellow wire attached to the detector.

Twist the screw-nut connectors back onto the twisted pairs of wires. Push the wires back into the hole.

Place the mounting plate back on the ceiling, over the hole. Reattach the screws. Restore the electric power.