Alarm going off but can't find out why

[jem16]

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]

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

 

[jem16]

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]

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]

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]

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]

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

 

[jem16]

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]

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]

Either bad or very bad.

 

[jem16]

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]

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]

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]

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]

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.