False alarms

[amateurandy]

Hello folks,

Firstly I would like to point out that I've posted this in the DIY Alarm Installers section; so please treat me gently!

My alarm (ADE Accenta G3), which I installed myself about 18 months ago AND HAVE SERVICED REGULARLY (as described very helpfully on this site) has had a couple of FA's recently. One was while the house was empty (full set) and was the Landing PIR; the neighbours (who have keys and codes) sorted that out as I was on holiday. The second was at night (part set) and was the Lounge PIR; that woke me up PDQ! In both cases all the relevant areas doors, etc were fully closed and there were no storms, power cuts or anything odd at the time.

I couldn't see or think of anything that might trigger it and checked inside both PIR's - clean as a whistle, no spiders etc. and no cobwebs nearby either. Cleaned them anyway for good measure.

Has anyone any suggestions what to look for, or is it "just one of those things"?

Thanks

[Guest]

If it's random zones triggering it then I'd suspect inteference\induced EMF or even a bunch of cables damaged, maybe trapped under the edge of a board or pulled tigthtly round a corner.

First thing to do is test all the resistances and voltages to see if anything has deteriorated.

[amateurandy]

Thanks,

I'm (almost) totally sure it's not trapped or damaged cable; I routed them very carefully well out of the way, plenty of slack, cutouts, etc. and nothing has changed since installation. But I have the means to test continuity, resistance, shorting between cores etc. so will do that.

I had been thinking of getting a spike suppressor. I can't offhand remember the name/model and supplier, but there have been plenty of references to them so I'll track it down. If I recall correctly there are 2 sorts, one for the incoming mains and another for the 12v circuits (fit inside the panel?). any comments anyone on which to use and why?

[Guest roonster]

yup you need a spike suppressor direct from the suppliers here:

http://www.actmeters.com/actmeters.htm

ACT1313 12V Spike Suppressor

Next to user error, induced AC voltage caused by electro-magnetic interference (EMI) is the biggest cause of false alarms. Alarm cables running alongside mains, telephone and other service cables, induce high voltages and electrical

[Mavrick_001]

Hi Andy, set your multimeter to ac, place one probe on the earth of the incomming mains cable THE EARTH and the other probe to a zone on the panel.... any will do just pick one side of a zone, this will give you a reading of induced ac on the panel, if it's above 10 I'd look at getting the above mentioned act1313 spike supressor. There are filters for the 240v side of things which choke surges and so on but I'd give the 1313 a go first before you start throwing money at it which it might not need.

[amateurandy]

Thanks everyone for your comments. A busy weekend ahead, I think.

[breff]

As maverick said except probes on earth and 12v dc.

[Adi]

Breff is right.

[amateurandy]

Hmmmmmmmmmmmmm not sure what my readings prove.

Tested as suggested; +12V to earth is minimal, 0.2VAC

BUT panel supply (i.e. effectively across battery) shows 29VAC (and 13.5VDC).

Does this imply that the panel power supply is faulty?

Just to add a further bit of (probably irrelevant) info - my house has overhead power cables. The electricity board have told me (and showed me) that Earth is clamped to Neutral. Every alternate telegraph pole has a long earth spike clamped to Neutral. And indeed the readings are identical if swapping Earth and Neutral.

[amateurandy]

Thanks for the advice everyone, I bought an ACT1313 as suggested.

Testing again with my better (more expensive) meter on the 20VAC range and I had about 15V induced AC which reduced to 0.12V AC after fitting the suppressor.

No more FA's I hope.