The strongest locks in the world mean nothing if a burglar can just break the glass on your windows or doors to get in. But a good security system will have a glass-break sensor that can set off the alarm if a windowpane is broken.
What is a glass-break sensor?
A glass-break sensor uses a finely-tuned microphone to pick up the sound of breaking glass. The benefit of this system over a detector that you place on a window is that these sensors can monitor whole rooms at once.
So if you have a big picture window in your living room, one glass break sensor will cover you just fine. They also do great at covering an area with a sliding glass door, which can sometimes be the easiest entry into a home. Even if you don’t have many accessible windows, it’s a good idea to monitor them with a glass break sensor to avoid weak links in your system.
How do glass-break sensors work?
When glass breaks, the sound it makes is in a very unique frequency. Sensors work by monitoring that frequency, and any noise in that frequency will trigger an alarm.
Most sensors cover anything within 25 feet, as long as the sensor is within “sight” of the window. The sensors are tuned to pick up glass breaking frequencies for a wide range of window glass, including plate, tempered, laminated, wired, coated and sealed insulating glass.
However, because they work by sound, they aren’t perfect in every situation. They need to be located away from air ducts and noisy equipment. They also may not work on windows with heavy coverings like drapes or wood-slatted blinds, which can dampen the sound.
However, you probably don’t have to worry about a broken water glass setting off the alarm. The vibrations made from other glass objects usually fall outside the frequency monitored by glass-break sensors.