Why do we refer to an alarm clock as going “off” when it actually turns on?

You turn the alarm on when you set it so it is already on so it doesn’t come on it is just waiting to go off in the same means as a ticking time bomb.

Ha ha I’ve never thought about why we say alarms are going off.

You set the alarm on, when its time the setting goes off and the alarm rings to alert you. Not sure if I am making sense here. lol