A hard-wired smoke detector uses the electric lines in a home for its power supply. You can remove a hard-wired smoke detector that has become defective and must be replaced yourself. Household tools will be needed, but no special electrical skills. You will also need to know the location of the fuse box and which circuit breaker affects the electric lines connected to the smoke detector.
Go to the fuse box. Trip the appropriate circuit breaker to discontinue the electric power to the smoke detector.
Place a ladder by the wall where the defective smoke detector is located; if the detector is ceiling mounted, place the ladder beneath it instead.
Twist off the smoke detector's cover using a counterclockwise motion. Place the cover aside. Remove the battery from the battery compartment inside the detector. Place the battery aside. (The battery is used as a back-up power supply in case the electricity goes out in your home.)
Remove the screws from around the detector using a Phillips screwdriver. Place the screws in your pocket for safekeeping.
Pull the detector off the ceiling mounting plate. Twist the screw-tab connectors off the pairs of twisted wires that are now revealed in a hole at the center of the ceiling mounting plate. Place the connectors in your pocket. Separate the twisted pairs of wires from each other. Dispose of the detector properly.
Twist the screw-tab connectors on the wires that are coming out of the hole at the center of the plate -- use a clockwise motion to do this. Push the wires inside the hole.
Remove the screws from around the ceiling mounting plate using the screwdriver. Place the screws in your pocket. Pull the plate off the ceiling.
Place the ladder away. Restore the electric power at the fuse box.