How Glass-Break Sensors Work

Your home should have multiple layers of protection. You've certainly heard that before. Motion detection is a critical layer of protection, and this is comprised of the simple act of unauthorized movement sensed as the result of breaking and entry. Glass break is similar in concept. One detects movement the other detects sound.

• Motion — The sensor detects when someone is moving about inside the house.
• Entry — The sensor detects when a door or window is opened.
• Breaking into — The glass break sensor detects when a burglar smashes through a window with a crowbar.

Many people don't know that the sensor for breaking into exists. This special kind of sensor detects the unique sound (in terms of frequency) of window glass being hit and then shattering. The sensor then sets off the alarm.

So in other words, the sensor doesn't wait for the glass to shatter. The detection starts when the crowbar or baseball bat makes heavy contact with the glass. This initial detection can be thought of as phase one. And phase two, the actual breaking of the glass, occurs just milliseconds later, setting off the alarm.

In a house full of windows, one sensor per room may be sufficient, covering three or more windows and even glass doors. And fortunately, it's not necessary to have your kid hit a baseball into a window to test out the sensor.

The device has a "test mode." You should produce a clapping sound (preferably with your hands). At the bottom of the sensor, a small light will blink, in response to the sound of the clapping, which simulates the sound of a window being struck.

Now if you don't see the light blinking, the sound wasn't detected. Make sure the sensitivity setting is on "high" in the device, and also check your windows; are they blocked by heavy curtains or furniture? If your hand clapping is weak, do you have a few wooden boards to smack together?

After you make the necessary adjustments, create the clapping sound again. If the unit is correctly installed, the light should blink.

If your child thinks he could trip the alarm by banging cymbals or dropping a glass on the kitchen floor, tell him don't even think about it. The break-into sensor system has already taken false alarms into account. So if a glass or china plate crashes to the floor, or the sound of windows breaking is coming from the TV, these noises will not trip the alarm.