FAQ Loss of AC Power

My house lights are on but the system has reported a "Loss of AC" or behaves like it's not getting power. What do I do?

Some security systems have a DC Power ON/OFF switch either on the main circuit board or on a small module in the alarm box. Make sure it is turned on.

Find the plug-in transformer that supplies power to your security system. It is about the size of your fist or half a brick, and is usually plugged into a regular duplex outlet. If you have trouble locating it, call us. We may be able to tell you where to find it. Make sure the transformer has not vibrated loose from its seated position, or been unplugged by an outlet-hungry workman.

! Most of these transformers have a tab with a screw that holds them so they won't fall out. The screw takes the place of the regular cover plate screw. If you need to remove the screw to pull out the transformer, you must tape or hold the metal cover plate so it won't slip down across the prongs as you remove or insert the transformer. If it does, it can cause a short circuit, burn, shock, eye injury or all of the above. At the very least, it will leave a nasty black mark and pits on the cover plate and prongs.

The transformer should be warm. (Some of them are normally too warm to hold for more than a few seconds.) If it is cold, use a lamp, radio, drop light or any other small appliance to see if the socket has power. If it doesn't, the circuit breaker may be tripped or defective. Dead outlets are common when a socket is supplied by a "Ground fault interrupter." Rainy conditions tend to provoke them to trip. (In accordance with current industry practice, we recommend that you have an electrician install a separate socket that is not connected to a ground fault interrupter, to avoid this nuisance.) Regular circuit breakers also go bad once in a while. They may even look like they are turned on, but in reality, they are not delivering any power to the circuit. It will take a qualified electrician to correct that problem. It is also possible for the outlet (or even just half of a duplex outlet) to be connected to a timer, wall switch or a separate circuit breaker. Review any recent electrical wiring changes to see if this may have occurred. The system transformer must not be plugged into any outlet that is switched, timed or fed by an electric eye. If necessary, ask your electrician to install a new outlet that is connected to a standard circuit breaker and is always turned on.

It is good practice to put a label on the circuit breaker that supplies your system and also have your electrician install a circuit breaker lock, especially in commercial premises where lights are turned on and off daily from the circuit breaker panel. Labeling and breaker locks are both required by the fire code for commercial fire alarms.

If the receptacle is worn out, the circuit is damaged or the breaker is bad, you can temporarily overcome the problem by running an extension cord to a known good outlet. Plug the system's transformer into the extension cord. Support the transformer in such a way that it can not rest against carpeting or other combustibles.

Sometimes outlets are fed by split sources. For example, the top half of an outlet could be live all the time, while the bottom half is switched, timed, fed by an electric eye, or supplied by an entirely different circuit breaker, to accommodate, say, an air conditioner at a particular window. If the unused half of the socket has power, but the transformer stays cold, remove the transformer and make sure that the other half of the socket also has power and that the transformer prongs are in good electrical contact with the innards of the socket.

In locations where a ground fault interrupter is required, an electrician may have already installed a dedicated outlet for your system. To satisfy code requirements, the unused half of that duplex receptacle will be dead. It is possible that someone could temporarily unplug the transformer, use the power, then unknowingly return the transformer to the dead half of the receptacle.

Don't "spark test" the transformer by putting a short circuit across its screw terminals! There is a fuse inside the case that is not replaceable. These transformers occasionally blow out during storms. If that happens, the only remedy is a new transformer. It is usually best to have us take over when you reach this stage of troubleshooting. If you decide to fix it yourself, be sure to use one with the correct output voltage and VA rating. If you experience a blown transformer more than once in a few years, consider having us supply a spare transformer that you can install yourself in a bind.