Many residential smoke alarms connect to the home electrical system as well as a battery. The battery serves as a backup should the power go out. When you need to service or replace the alarm, you should turn off the power. This should be a simple process. However, even something as simple as switching off a circuit breaker can prove difficult when you have no idea which breaker operates the alarm.
Open the door of your electrical panel box. There is usually a sheet on the inside of the door indicating what each circuit breaker controls. Look for the one that controls the smoke alarms.
Press down the raised end of the circuit breaker to shut it off.
Take out the smoke alarm battery if you can't tell which circuit breaker operates the alarm. The battery compartment is usually on the side or bottom. The alarm might chirp or sound off when you remove the battery. If not, the LED light will remain illuminated.
Go back to the electrical panel box and turn off one circuit breaker. Check the alarm. If it stops chirping or the LED light is no longer lit, you found the correct circuit breaker.
Turn the breaker back on and move to the next until you find the one that operates the alarm. When you find it, make a notation on the electrical panel door so it can be easily identified in future.