So today, I got my second piece of the fire alarm and was putting it together, but when I pulled the pull station, nothing happened. I later noticed that I didn’t have enough voltage for the fire alarm and pull station, so I will have to buy a fire alarm power supply. AC-powered and plugin smoke and CO alarms rely on a continuous source of electricity to operate. The primary power source for this type of alarm is the electricity from your home. If the electricity in your home goes out, these alarms automatically switch to their second power source, the backup battery. The backup battery should power the alarm for a minimum of 7 days without electricity to keep your home protected. Modern hardwired alarms require a battery backup. Even though my fire alarm does not have a backup battery, it can still fail. So I hope you enjoyed my blog, bye duh.