Motion & Glass Break Detectors

[rbcaputo]

I came across this unit which does both motion and glass break detection http://www.smarthome.com/71242.html.

Does anyone have any experience with this? Is it a good idea to get a combined sensor like this one. It would be simpler and neater. What sensors are you using?

I have a Caddx NX-8E alarm system.

Thanks

[DC]

I can't speak for the quality of these particular sensors but I can tell you from experience as a police officer that the majority of false burglar alarms are caused by glass break sensors. A low quality glass break sensor can be tripped by thunder, loud music, a car backfire, wind, basically anything that can cause the glass to vibrate a little. Supposedly, better quality ones (ie, more expensive) are less prone to these kinds of false alarms.

[rbcaputo]

One reason I'm considering glass break detectors for my windows is that they are casement windows. I have cocluded that it's useless to put magnetic contacts on these windows because one has to turn the handles on the inside in order to open them. In order to get at the handles from the outside, you would have to break the glass first. Is this what others are thinking as well, i.e. no magnetic contacts, just glass break and motion detectors? If so what units are you using? Any comments on the combined motion and glass break detector shown in first posting?

[anogee]

First of all, I would not recommend this unit. The reason is simple, the best placement for a glass breakage detector is a poor one for a motion sensor, and vise versa. Typically IR motion detectors are placed in the outside corners of a room so they DON'T point at windows because pointing at windows can cause false alarms. Glass breakage detectors have to point at windows to "hear" the glass breakag, usually you place them on an inside wall facing the glass.

I wouldn't worry about false alarms for glass breakage detectors. With modern ones install correctly, that almost never happens. Just set it up so the glass detector is only active in "away" mode, not off, stay or night. Break a dish or glass and it likely will be set off.

Also, make sure you check with the sensor maker to see their requirements for window size. Many will not work on small windows. They usually need to be larger windows.

[rbcaputo]

Anogee, note that the recommended location for the combined motion / glass break detector is on the ceiling. In my case this would be about the centre of the romm with windows and patio doors on 3 sides. Does that alter your thoughts regarding this unit? Is the ceiling a good location for a motion and/or glass break detector?