How do I stop an alarm on a home security system when the power is off?

Updated July 20, 2017

A seemingly unsolvable problem can stymie homeowners or tenants who have home security systems: The house alarm is running when the power is off and the keypads do not work. This can be caused by either a dead backup battery or a power surge that reset the system. Regardless, the annoying alarm siren needs to be shut off, and you can accomplish this yourself.

Find the main alarm box. This is usually located in a master bedroom, master closet or sometimes a utility room. The alarm box will likely have a decal or other markings from your alarm system provider. It will also have a line running from it to an adjacent power outlet.

Remove any securing mechanism and unplug the box -- these are often secured to the outlet with a screw.

Unscrew the outer metal casing to open the alarm box. You'll find a fairly large battery inside -- this is the backup battery for use when the power is out.

Unscrew and detach the backup battery from any wires running to it. You may need pliers or your screwdrivers to do this properly. You should hear your alarm sirens stop once this step is completed. If they are not clearly marked, mark the battery's positive/negative wires with tape and a pen at this point so you can reattach this or a new battery later. Your PIN/alarm number will no longer work now, as you have reset the system. Your alarm system is also not functioning at this point.

Call your alarm company -- the number is usually on the alarm box itself -- and explain what you have done. The company will give you a reset pass code to use to get your system online again, and the alarm company may be able to reset your system remotely. If not, it will send a technician out to reset the system manually or replace your backup battery.


For safety, use rubber or wooden-handled tools when possible to avoid corrosive materials or electrical exposure. To clean up after a leaked battery, mix about 1 tsp of baking soda in 2 cups of water. Wet the affected area with a dampened sponge, and wipe the compartment clean. Dry the compartment with a towel, and replace the batteries. Always change your backup battery when you see a "low battery" indicator on your keypad. This can prevent power-outage issues in the future.


Any activity involving electrical cut-off or battery replacement carries an inherent risk of shock or corrosive exposure. Be sure you are comfortable performing these actions, or serious injury or death can result. If you have any doubts about your ability to carry out these steps, please contact your service provider or an electrical professional. Old batteries may leak corrosive materials -- be sure to use rubber gloves. Always dispose of old batteries properly, even if they have not leaked.

Things You'll Need

  • Screwdrivers, Phillips and straightedge
  • Pliers
  • Construction or scotch tape
  • Pen
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About the Author

Gregory Scott has written professionally since 1995. His work has been featured in "Inside the Seahawks" magazine, "American Chronicle," "Linux Today" and on various online technology news sites. Scott continues to specialize in writing for the high-tech space. He received his Bachelor of Science in communication from Seattle Pacific University.