Glass Break Sensor - How Does It Work & Where to Put It

This post was updated on December 30, 2019.

Let’s address another 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, how effective they are, and where to place glass break sensors. Then you can make an informed decision about whether your home would benefit from this device.

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.

When a pane of glass shatters, it creates a distinct sound frequency. An acoustic 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 sensor devices work by “feeling” the unique vibrations of shattering glass. To function 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 they are annoying to set up. As a result, Frontpoint’s glass break sensor uses acoustics to trigger alarms and keep your home safer.

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, this 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.

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 could trigger acoustic glass break sensors, such as:

• A drum set’s snare drum
• Some large captive birds, like cockatoos

Frontpoint’s glass break sensors are designed to detect a specific sound frequency emitted when a glass panel is broken. That way, you don’t need to worry about false alarms caused by dropping a glass in the kitchen or hearing glass break on the TV.

If you have questions about Frontpoint glass break sensor sensitivity, you can call customer support at 1-877-602-5276.

Once you have your glass break sensors, you need to set them up:

1. 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 windows you most want to protect.
2. 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. Glass break sensors have approximately a 20-foot radius.
3. Step Three: Select a location between 4 feet and 20 feet from the window(s) that you want to protect—this can be on a wall or on the ceiling, or on a table or a shelf. Do not place the glass break sensor on the same wall as the window. Then ensure that location is within 100 feet of your Frontpoint Hub or Control Panel. Lastly, the sensor should have a clear line of sight to the window(s). This means furniture or decorations should not be placed in front of the sensor.
4. Step Four: Mount your sensors. The sensor comes with adhesive pads that will stick to a wall or ceiling. Ensure the mounting surface is clean and dry before adhering.

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.

Want to design your own home security system setup? Read more in our What is a DIY Home Security System blog.

Frontpoint keeps families safer and more connected in their everyday lives. We've been revolutionizing the home security industry for over a decade. And we're just getting started. To shop DIY home security systems, check out our Security Packages. If you have questions or would like to discuss a quote, contact us at 1-877-602-5276.