In our previous two installments of Home Security 101, we covered wireless door and window sensors and wireless motion sensors. Now let’s address the third line of defense in a standard intrusion alarm system: the glass break sensor, sometimes called a broken window alarm. This device is triggered when a pane of glass shatters nearby it.
I will explain how glass break sensors work and perhaps more importantly, how effective they are. Then you can make an informed decision about whether your home would benefit from this sensor.
How Does a Glass Break Sensor Work?
There are two types of glass break sensors: acoustic and shock. They work differently, but have the same goal: to set off your home alarm when triggered.
Acoustic glass break sensors work by “hearing” the sound of breaking windows. Shock sensors work by “feeling” a physical disruption of broken glass.
Acoustic Glass Break Sensors
When a pane of glass shatters, it creates a distinct sound frequency. A glass break sensor works by “hearing” the sound of shattering glass, then triggering an alarm. That means one sensor can cover lots of windows (and glass doors) in a single room.
Shock Glass Break Sensors
Shock sensor devices work by “feeling” the unique vibrations of shattering glass. To work properly, they must be physically attached to the window or door they are protecting.
Although shock sensors are known for triggering fewer false alarms than acoustic sensors, they have significant drawbacks. For example, you need to mount a sensor on each window you wish to monitor. This can get expensive—not to mention annoying to set up.
Personally I prefer acoustic, but of course, the best glass break sensor is the one that works best for you. Effective home security is all about matching the right sensor to your lifestyle, home layout, and preferences.
Do Glass Break Sensors Really Work?
You might say to me, “Peter, this sounds all well and good, but are glass break sensors effective? And if door and window sensors and motion sensors work so well, why do I need a glass break sensor?”
The truth is, you might—or you might not.
Door and window sensors and motion sensors are fundamental parts of a home security system. I absolutely recommend those to everyone, regardless of home layout or size. However, you don’t want to have just one or two lines of defense protecting your home and family.
For instance, say a home relies solely on door and window sensors. If an intruder enters that home by breaking a window or a glass door, the door and window sensors will prove inadequate. Why? Because the window or door frame itself will remain in place, even after the pane is broken, the door and window sensors will not be triggered. The intruder will remain undetected.
Now let’s say that home also has motion sensors. This is an improvement, but the intruder can still try to avoid venturing near the motion sensor and remain undetected.
This time, however, let’s say the home also has the third line of defense that is glass break sensors. The intruder would have been detected the moment they broke the glass window or door, before even entering the home.
A glass break sensor is an extra layer of defense to make your home even safer. While it is not what I’d call mandatory, a glass break sensor absolutely helps to create a more secure home. What one sensor cannot detect, another can—and they start tag teaming to keep you and your family safe.
Glass Break Sensor Sensitivity
False alarms may occur if someone accidentally drops, say, a glass vase within the sensor’s proximity. (Often, a glass break sensor’s range is 20 feet in any direction.) There are a few other sounds that have been known to trigger acoustic glass break sensors, such as:
- Cupboard door slam
- A drum set’s snare drum
- High-pitched dog barks
- Some large captive birds, like cockatoos
You may be able to combat false alarms by testing the sensitivity of your sensor, so you know what sets it off.
Where to Place Glass Break Sensors
I’m going to take the liberty of assuming that I have convinced you to opt for acoustic glass break sensors. Now let’s set them up.
- Step One: For effective glass break sensor placement, you need to think like a burglar. So consider which windows are most easily accessible from the outside. Which window would you use if you were breaking into your house? Usually the answer includes any windows or glass doors on the ground floor or at the basement level. Those are the panes you most want to protect.
- Step Two: Decide how to distribute your sensors. You want to use as few sensors as possible to cover as many windows as possible. Areas with multiple windows are a natural starting point. For example, if you have a room with several windows and a sliding glass door, you can likely protect the whole room with a single glass break sensor.
- Step Three: Mount your sensors. Wireless glass break sensors mount on the wall or ceiling, and don’t have to “point” at the glass they are protecting—they just need a clear “line of sight” to do their thing.
There are a few basic rules for proper glass break sensor placement. For example, you must mount the sensor at least 4 feet away from any of the glass panes you wish to protect. It should be on a different wall from the pane. Also, never place a glass break sensor in between two windows on the same wall. There are several other factors, but if you are using a Frontpoint system, our Setup Wizard will guide you through every step of the easy peel-and-stick mounting process.
Until Next Time
The best alarm companies are committed to providing you with the protection and peace of mind you deserve. Adding one or more wireless glass break sensors to your system could be the right call for your home.
Now we’re another step closer to designing a complete home security system. There are a few more sensors to cover before we get there, so make sure to join us here for the next round.