Burglars - are shock sensors useless?

yoke

talking to a guy who works for (or owns) a company that installs monitored house alarms, he kept insisting that shock/vibration sensors on windows are completely useless because apparently "anyone with a screwdriver can press down on it and shatter the glass without setting off the sensor".

Is this true? Even if the window is double-glazed?

I don't believe him, but since it would cost a lot in broken windows to test this thoroughly, I'd like to hear other people's opinions on shock sensors on windows - anyone have any anecdotes where a robber (or a 'friend') broke a window without setting off the shock/vibration sensor?

368100

yoke wrote: »

talking to a guy who works for (or owns) a Dublin company that installs monitored house alarms, he kept insisting that shock/vibration sensors on windows are completely useless because apparently "anyone with a screwdriver can press down on it and shatter the glass without setting off the sensor".

Is this true? Even if the window is double-glazed?

I don't believe him, but since it would cost a lot in broken windows to test this thoroughly, I'd like to hear other people's opinions on shock sensors on windows - anyone have any anecdotes where a robber broke a window without setting off the shock/vibration sensor?

Press down on it with a screwdriver in what way? To stop it moving?

Shock sensors monitor for a large shock eg a broken window, they also monitor for a series of small tap like hits which should pick up a glasscutter. Given that sensitivity can be set too I would say it's far from useless.

If you didn't have them there wouldn't be a clean option for full perimeter protection for example at night...when you want to move around the house with the alarm set....open to corrEcton if there's another option as it's been a few years since I've installed these systems

yoke

I think he said "where the glass meets the window frame, press down hard on the glass with the screwdriver to bend it until it cracks"

368100

yoke wrote: »

I think he said "where the glass meets the window frame, press down hard on the glass with the screwdriver to bend it until it cracks"

Given the sensitivity is set correctly it should still set off the sensor with a series of taps/bangs even though theyre light. Id imagine Double glazing would take some pressure to break....never mind triple glazing so I can't see how it wouldn't set it off. Maybe theres a chance with single glazing.

Wiring for shocks in an older house is hassle, having to drill up into the cavity at every window. Pir wiring is usually less hassle and PIRs are more expensive than shock sensors so maybe there's some sort of motivation in his comments in that.

yoke

Yeah he definitely has a vested interest as his company only installs motion sensors, which is why I didn't believe him.

That said, I believe most modern wireless alarm sensors incorporate a shock sensor and a contact sensor (to detect opening/closing windows), and theyre screwed onto the window with no wires - am I right?

I've read there's a third type of sensor, which is called a "glass break" sensor, which is basically a microphone and a microprocessor that scans for the sound of glass breaking, but I don't know much else about this, ie. is it available for commonly used alarm systems in Ireland, etc.

368100

yoke wrote: »

Yeah he definitely has a vested interest as his company only installs motion sensors, which is why I didn't believe him.

That said, I believe most modern wireless alarm sensors incorporate a shock sensor and a contact sensor (to detect opening/closing windows), and theyre screwed onto the window with no wires - am I right?

I've read there's a third type of sensor, which is called a "glass break" sensor, which is basically a microphone and a microprocessor that scans for the sound of glass breaking, but I don't know much else about this, ie. is it available for commonly used alarm systems in Ireland, etc.

Yes, a lot of the shocks are now wireless...batteries last long time too with using very little power.

I don't know about the third sensor as it's a few years since I've been in that game, doesn't sound overly reliable to me to be looking for the sound of glass breaking but maybe they work OK.

In any event, I'd be steering clear from who you were speaking to as they seem to have their own agenda with what they want to install...or failing that at least get a second company in to quote and see what they would advise installing.

kub

I am in this business a long time and in my own experience any guy in our profession who comes out with a line like that with regard to shock sensors has very limited experience with them.

I find that usually they are afraid of them because they have not got the where with all to fault find shock sensors.

yoke

Thanks for the replies everyone.

I've decided to go with a different company as per everyone's advice, and get shock+contact sensors on the windows and doors.

That said, I'm quite surprised at how high the quotes are for additional sensors generally - I'd always thought it was just a case of screwing them into the window frame, making sure it's aligned when closing the window, and then adding them on the head unit and setting the sensitivity - is it something that's finicky and hard to get right (so it's better to go with a PSA licensed installer), or is it something anyone could do easily?
If it's easy, then I'll get the basic head unit and a couple of sensors installed by the PSA guy, and buy and install the rest myself.

I am planning to get a relatively basic system installed now and buy some extra PIR cameras and a couple more shock+contact sensors and install them myself, but I haven't done this before so I'm basically hoping someone can warn me if it's a minefield and I'm likely to make a balls of it

Cheers

368100

yoke wrote: »

Thanks for the replies everyone.

I've decided to go with a different company as per everyone's advice, and get shock+contact sensors on the windows and doors.

That said, I'm quite surprised at how high the quotes are for additional sensors generally - I'd always thought it was just a case of screwing them into the window frame, making sure it's aligned when closing the window, and then adding them on the head unit and setting the sensitivity - is it something that's finicky and hard to get right (so it's better to go with a PSA licensed installer), or is it something anyone could do easily?
If it's easy, then I'll get the basic head unit and a couple of sensors installed by the PSA guy, and buy and install the rest myself.

I am planning to get a relatively basic system installed now and buy some extra PIR cameras and a couple more shock+contact sensors and install them myself, but I haven't done this before so I'm basically hoping someone can warn me if it's a minefield and I'm likely to make a balls of it

Cheers

As long as you're sure you can connect them to the main panel and configure them properly I don't see why not. If you have a discount on your home insurance for having an alarm I don't know how it might affect not having a fully centitled system.
Also, sensors should be located as centrally as possible on the windows to ensure effectiveness.