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We currently have a house alarm that appears to be wired to the upstairs lighting circuit, and any time a light bulb blows the alarm is set off, is this normal?

We've recently moved into a house with a wired house alarm that appears to be wired to the upstairs lighting circuit. Any time a light bulb blows its trips the fuse and sets off the house alarm. It doesn't sound like its the full alarm, just a ringing outside, a little like a car alarm volume.
We are unable to disable the alarm as there is no power to the alarm keypad.
Once we reset the fuse, it then triggers the full house alarm and we are able to disable the alarm.
Additionally, if there is a power cut to the house, the alarm is triggered, again the outside ringing only, but due to the power cut we cannot find a way to switch off the alarm until the power is restored as there is no power to the keypad.
Once power is restored, again the fully volume alarm is sounded until we disarm.

We recently had a power cut in the middle of the night, and I found it very embarrassing that I could not stop the ringing until power is restored. This cannot be normal that I cannot shut down the alarm just because there is no power to the keypad.

3 Answers from MyBuilder Electricians

Best Answer


As Kelvin has said above, your alarm will have a small rechargeable battery hidden inside the panel, these are the Achilles heel of any maintained alarm system. they are not hard to change but be aware that once you open the panel (usually only 2 screws) it will trigger a tamper condition and set the alarm off. changing the battery is a simple task of isolating the panel and swapping the battery.

What you are currently experience is the battery back up in the bell box ringing to say that the panel has lost power.

However i would see if you can get a alarm engineer or electrician to take a look as a battery is a service item and only has a life span of around 3-5 years so your system is probably well over due a once over. they will also be able to confirm the origin of the power supply to the panel. the alarm ideally should be fed from its own "clean" supply as the lighting circuit will cause it to go off every time a bulb blows, however you may find that the problem is RCD related and its dropping out the alarm circuit when the RCD operates.

Good luck and all the best.



Answered 9th Sep 2011

You should have a separate control box somewhere in the house were all the wiring is terminated inside usually hidden in a cupboard of even in a loft you should find a Rechargeable battery inside these do fail and can cause the problem you discribe the alarm should be serviced regularly and the battery would be tested then and replaced when needed.
put the job up to service intruder alarm on my builder then you should sleep better


Answered 8th Sep 2011

What's happening is when you lose power in the panel it stops charging the outside bell battery, the bell then things that someone has cut the power on purpose and start sounding, the result of this would mean that the battery that takes over in the event of a power cut should still carry on charging the Bell, which in your case it's not meaning the battery has failed, therefore you have two options
1. The simple one would be to change the battery normally there 12 volt 7 amps depending on the alarm panel.
2. Or you can disconnect from outside Bell 12-volt supply and the battery connection this will permanently disable the outside Bell


Answered 27th Sep 2018

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