How do I add a hardwired smoke detector?

Hardwired smoke detectors connect to a 120-volt circuit and are interconnected so all alarms sound when one detects smoke. Turn off power at the breaker. Run 14/3 wire from an existing smoke detector or junction box to the new location. Connect the black, white, red (interconnect), and ground wires matching colors. Install the detector base, attach the unit, and test the interconnect function. Follow local code requirements.