ADT alarm going off despite electrician disconnecting

[Janejanejane78]

Hi,

I moved into a house 6 years ago with an ADT alarm. I never had any info for it or had it commissioned. 4 years later it started going off for no reason so I had an electrician come in and disconnect the mains and the battery from the alarm box in my cupboard. 2 years later and it is going off again but seems to be coming from the ceiling void between the 2 floors. From googling it seems there may be a bell box with a back up battery. I can't find a bell box anywhere - not on the outside of the flat. A few questions:

1) is it possible that the bell box could have been installed above the ceiling?
2) How long might it take for the battery to run out? Otherwise I may need to get a hole cut in my ceiling. This is far from ideal.

Any helps would be really appreciated.

Thanks!

Jane

 

[EightyTwo]

It should have stopped after 20 minutes...

If it's 2 years on, it is unlikely to be the intruder alarm - unless you live in a mansion with dozens of detectors and an additional power supply that your electrician missed...

 

[Janejanejane78]

Thanks for your reply. Oh I wish it had gone off after 20 minutes.

It is still most definitely going off 12 long hours later. I do live in a block but the source of the noise has been built into the ceiling cavity. So I have no way of knowing how it is connected. I can't imagine it is from the block as it is a private alarm, that no one else has.

 

[EightyTwo]

So what sort of noise is it? Is it a WAH-WAH-WAH? A bip-bip . . . bip-bip? A WAAAAAAAAAAAA...H? A WEE-OOO, WEE-OOO, WEE-OOO? And how loud is it?

The reason that I ask is that it it might not be the intruder alarm or it might be coming from a different flat or outside. Some sounds at certain frequencies can be very difficult to locate. It is unlikely that anyone has 'buried' a sounder in the ceiling. If you have lights fitted into your ceiling nearby, you could try taking one out (when it's been off for a while and is cold) and sticking a camera or your phone through the hole and taking a photo/video to see what's up there...

Another thought - could it be a failing transformer for a dichroic (halogen) downlight? Can you stop the noise by turning the lights off?

Or, possibly, an in-line extractor fan with a worn out bearing? These can be placed in the ceiling void...