How to install kidde smoke and carbon monoxide alarm hardwired

Replacing a hard-wired smoke detector is almost as easy as replacing a battery-powered version. New alarms are inexpensive. If your old alarms are connected to three wires as shown here, that means the alarms are interconnected — when one alarm detects smoke, they all howl.

A series of hardwired smoke detectors in different rooms are powered by a common electrical cable. The cable runs from one detector to the next in piggyback style. At each detector location, the cable runs into an electrical box. The smoke detector is connected directly to the electrical cable's wires.