Alarm going off but can't find out why

jem16 · 3 Oct 2010

I have had a problem with my alarm since around the end of June.

For a few weeks it seemed to be a pattern of one particular zone ( Zone 3) with 2 PIRs causing the alarm to go off. It always seemed to be a Wednesday night around 11:30pm to 12 midnight. Nothing however seemed to be out of place.

The engineer has been out to check it and checked over the wiring which all seemed to be fine. He checked the 2 PIRs and again both seemed fine apart from one contact screw being loose so that was tightened. Next time same thing happened so he replaced both PIR circuit boards.

A few days later it happened again only this time that same zone (3) plus another zone (4) with one PIR triggered. Again no known cause, again a Wednesday night.

Next time it happened about 2 weeks later but this time during a Tuesday day time. Same zone 3 as always and again no immediate cause. It was a windy day and shadows were dancing around on wall but no other thing I could see.

So engineer back out and changed over Zone 3 into Zone 7 on Control Panel jsut in case Zone 3 had a problem at the panel.

A day later alarm went off again although I don't know when as I was away for the weekend. This time it was Zone 2 ( another PIR ) which triggered it first followed by Zone 3 and Zone 4. This was 9 days agao.

I'm at a loss to what is causing these alarms. Can a mouse set off a PIR? I have set up mouse traps in the main rooms but nothing caught so far. The alarm has not gone off again either.

Is there something else that could be causing these alarm situations?

joe-90 · 3 Oct 2010

Did he check for a a duff battery dragging the voltage down?

jem16 · 3 Oct 2010

joe-90 said:
Did he check for a a duff battery dragging the voltage down?

No he didn't check the battery - probably because this was a new system installed in April so battery was new then.

Can I ask how the battery would be a factor on a mains powered control panel? -I thought the battery was only for backup purposes in the case of a power cut.

joe-90 · 3 Oct 2010

The battery works like a big smoothing capacitor to prevent voltage spikes. The voltage regulator feeds into the battery and the battery feeds the panel. If the battery goes open circuit then those spikes get passed into the processor and cause problems. If the battery goes short circuit then it is much worse as the regulator eventually packs up and the panel is knackered. The battery failing is the main cause of panel breakdown by a long, long, way.

jem16 · 3 Oct 2010

Thanks.

I have found it very odd that 3 separate zones have been going off together - all with PIRs. yet other zones with door contacts have been unaffected.

Could a duff battery cause this?

oasistechnical · 4 Oct 2010

what system (control panel) do you have fitted?
if you get a small electrical surge, this can cause spurious activations,
get the engineer to check that you do not have any mains born voltage (he should know how to do this if he is a good engineer.

also get him to check the circuit resistance on ALL devices to ensure they are within tolerance.

batteries can and do cause faults, but if the system is fitted with a new battery this should not be the case.

we fit, automatically, a mains filter available via ACT to prevent spikes etc,
also there is one available for your 12volt (detector supply) cabling,

both are good,

and, yet another and, if you have an overhead electrical supply (TT TN-S ) this could cause problems.

hope this helps

John

joe-90 · 4 Oct 2010

Check that the activations don't coincide with something like a washer switching on. If the suppressor has failed you'll get spikes.

jem16 · 4 Oct 2010

joe-90 said:
Check that the activations don't coincide with something like a washer switching on. If the suppressor has failed you'll get spikes.

I did think about that but nothing switching on at that time.

jem16 · 4 Oct 2010

oasistechnical said:
what system (control panel) do you have fitted?

Its an Accenta/Optima control panel.

if you get a small electrical surge, this can cause spurious activations,
get the engineer to check that you do not have any mains born voltage (he should know how to do this if he is a good engineer.

also get him to check the circuit resistance on ALL devices to ensure they are within tolerance.

He's an electrician rather than a specific alarm engineer. Don't know if that makes him good or bad.

joe-90 · 4 Oct 2010

Either bad or very bad.

jem16 · 4 Oct 2010

Spoke to the electrician tonight.

He's thinking along the lines of voltage spikes too so will bring along a new battery and check out the current one at the same time.

I had an Accentua/Optima fitted ofr 20 years which caused no problems at all. Only changed it in April as the keypad on the old control panel was getting quite worn. PIRs were totally replaced at the same time. The only thing kept was the door contacts.

jem16 · 16 Oct 2010

Update.

No further activations for 3 weeks now. Emgineer/electrician came out yesterday and replaced the battery. The original battery was showing as having 13v so not sure it is the battery itself.

However I asked him to test what would happen if there had been a small power cut by flicking off the circuit breaker for the alarm - outside siren sounded straight away. As soon as power was restored whole alarm sounded. This was with the original battery in. He said that the battery should not have allowed that to happen so it either is the battery or the control panel itself.

I assume that is correct?

New battery fitted and same thing happened when switching off circuit breaker. However I'm to give it 24 hours to fully charge up then try flicking the circuit breaker again. If it goes off he will replace the control panel.

josh451 · 16 Oct 2010

jem16 said:
Update.

No further activations for 3 weeks now. Emgineer/electrician came out yesterday and replaced the battery. The original battery was showing as having 13v so not sure it is the battery itself.

However I asked him to test what would happen if there had been a small power cut by flicking off the circuit breaker for the alarm - outside siren sounded straight away. As soon as power was restored whole alarm sounded. This was with the original battery in. He said that the battery should not have allowed that to happen so it either is the battery or the control panel itself.

I assume that is correct?

New battery fitted and same thing happened when switching off circuit breaker. However I'm to give it 24 hours to fully charge up then try flicking the circuit breaker again. If it goes off he will replace the control panel.

Checked the Battery Fuse?
Just a thought

jem16 · 16 Oct 2010

josh451 said:
Checked the Battery Fuse?
Just a thought

Not that I'm aware of. I wasn't aware there was a fuse.

Tried switching off the circuit breaker again after 24 hours, this time with the alarm fully set.

Same result - siren sounded when power was cut. When power restored full alarm sounding. After I switched off the alarm - zones 2,3 and 7 were all showing ( basically all the PIRs ) plus Zone 1 which I had to set off to get back in the house.

So it does appear to be the panel or as suggested the battery fuse.

jdk · 16 Oct 2010

I would agree with Joe 90

This problem sounds very much that there either a dodgy battery or lack of supply either fuse or low voltage. The PIR's reqiure a constant 12v voltage to operate when power is off they will go into alarm where as a door contact is not affected. This would also answer the query on voltage spikes, the batery would smooth these out.

The battery requires a load test not just voltage. A duff battery could still show 12 or 13 volts. If a load tester is not available connect a car indicator bulb across the battery whilst testing voltage anything lower than 11v indicates a problem.

diynot

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Alarm going off but can't find out why

Similar threads