Alarm Curiosity

[Mattenstein]

Hi all

I wonder if someone could indulge me in my curiosity as to why false alarms occur when they do.

Backstory: I live round the corner from a housing development c 1998 and remember when the houses were first built and occupied there was a regular cocophony of false alarms left, right and centre. I am sure they were all ADE Optima panels, but who installed them and what they did wrong is anybody's guess.

Anyroad, I just had a power cut tonight and it got me wondering what makes alarms sound when the power goes out, and what makes them sound when it comes back on?
Am I right in thinking that if an alarm sounds when the power goes out it is because the battery in the panel is dead and the siren sounds due to the loss of power from the panel, and that if it sounds upon restore of power it means either the siren battery was dead or they both were?

Thanks in advance ot anyone who can help and doesn't think I'm up to no good lol

 

[Handymanjo]

False alarms can occur has you say faulty battery.
Most problems are from poor installation and incorrect siting of equipment eg,pir facing letter boxes,pir sited above radiators.
Poor maintenance, people do not have systems serviced for years and this means that faulty batteries are not found.
Cleaning around detectors, spiders webbs across lens,objects hanging in front of devices.
Operator error.
Faulty equipment.
The list is endless.

 

[Mattenstein]

False alarms can occur has you say faulty battery.
Most problems are from poor installation and incorrect siting of equipment eg,pir facing letter boxes,pir sited above radiators.
Poor maintenance, people do not have systems serviced for years and this means that faulty batteries are not found.
Cleaning around detectors, spiders webbs across lens,objects hanging in front of devices.
Operator error.
Faulty equipment.
The list is endless.

Thanks for the reply and yeah I get there are a lot of possible causes. I was just wondering about the false alarms that occur due to power failure though and why some alarms go off when the power does, and some when the power is restored. It happened in my neighbourhood last night.

 

[sparkymarka]

In other words …all the tight arses who never have it serviced or at least replace the back up battery every 5 years ….

 

[delmel]

In that period there were a lot of, and probably still is a lot of Crap PIR detectors. These were unreliable and had crap fronts where bugs would move inside the sensors. An alarm is only as good as the equipment and the installer.

 

[sparkymarka]

In that period there were a lot of, and probably still is a lot of Crap PIR detectors. These were unreliable and had crap fronts where bugs would move inside the sensors. An alarm is only as good as the equipment and the installer.

There’s allways been crap pirs , some people just like to fit cheapest one they can find …

 

[Handymanjo]

Power surges or spikes are very common.
Alarm cables run with mains cables causing induced voltage pick up spikes causing alarm to go off.

 

[secureiam]

Like everything in life.

maintenance (so many dont maintain devices, just look at the accentas on here with burnt out components due to battery failure)
Correct device for the job
Correctly installed (see so many devices installed that are facing windows, above radiators, next to mains power and so on)
faulty devices, water damage and so on.

not all activations are truly false, ie there is a cause.

birds, pets, rodents, insects etc etc

 

[TiredandGrumpyReally]

if mains power fails, the back up battery should kick in, so unless its a long power cut, you shouldn't notice any difference outside. if power cuts out, and the siren outside sounds, that generally means there's not enough voltage in the back battery to hold off the siren- bad battery(whether the battery has failed, or hasn't been changed in years...).