Why do my smoke alarms go off when the power is off?

Answer by  Melissa101010 (4405)

Your smoke alarms may go off when the power is off because it alerts the alarm when your power goes off. The alarm may notice something different and that is why it goes off.

Answer by  dogownernj (82)

Your smoke alarm must be connected to the electrical wiring in your house. It goes off to warn you that the power has been disconnected. This is a safety measure so that you can be aware that your smoke alarm is not working. If you have a smoke alarm that is battery operated this does not happen

Answer by  Moi (88)

It could be due to old batteries or, depending on your particular alarms, it could be a sensor that tells them to go off when there's a power failure.

Answer by  Shelley59 (68)

I am almost certain it is a requirement for smoke alarms to have battery backup. All smoke alarms I have seen have a 9V battery.