How Do Glass Break Sensors Work?

Glass break sensors provide an additional layer of protection against burglars and other would-be bad guys. These sensors alert you and your home security company if a glass window or door breaks, helping to curtail robberies and burglaries.

Does your home security system include glass break sensors? If it doesn’t, it should. According to the FBI, a burglary occurs every 25 seconds or so in the United States, a fact that highlights the need for the most advanced and up-to-date security system.

If your home’s alarm system fails to include glass break sensors, also sometimes called broken window alarms. You’re leaving your home vulnerable to would-be burglars. Glass break sensors let you (and your alarm monitoring company) know immediately if a bad guy breaks your window. Since most burglaries in the United States start with a perpetrator forcing their way into the home through a window or door, glass break sensors are essential to an effective home security system.

How Do Glass Break Sensors Work?

Infographic of a person breaking into a house with glass break sensors

Would-be thieves rarely have the time or the know-how to pick a lock, so most just find a weak point in the home to make their way inside. Windows and glass doors are typically the weakest entry point because they can easily (and quickly) be smashed, allowing the intruder to gain entry with minimal effort.

Fortunately, glass break sensors pick up on the sound of breaking glass and splintering wood. Depending on the type of sensor, this occurs either through sound wave frequencies or vibrations. These sensors continually monitor your home for any audible sounds of glass breaking. So, if a burglar smashes your window trying to gain unlawful entry into your home, a glass break sensor detects the sound, triggers your home security alarm, and alerts authorities and your alarm company to the event. Sensors that detect breaking glass are a robber’s worst nightmare.

Glass break sensors may be one of two types—acoustic and shock. Acoustic sensors hear sounds, and shock sensors detect vibrations.  

Acoustic glass break sensors work by picking up on the distinct frequency of sound created when a pane of glass shatters. This type of sensor essentially hears breaking glass and triggers your home alarm system as a result. Because of the technology that powers acoustic glass break sensors, one sensor provides coverage for multiple windows and glass doors within the same room.

An acoustic glass break sensor detects the sound of breaking glass or splintering wood from as far away as 20 feet. Each sensor has an onboard microphone that continually listens for the specific glass break frequency that allows it to determine that glass has been broken or that the wood surrounding the glass window has been splintered. Most home security companies recommend that acoustic glass break sensors are installed on all ground floor windows and doors, largely due to the fact that most criminals gain entry to the home from street level.

Shock glass break sensors operate on the same principle as the acoustic glass break variety, but they pick up and detect vibrations caused by the motion of the glass breaking or wood splintering instead of sound frequencies. When these sensors detect these specific vibrations, they trigger an alarm. This type of sensor must be positioned directly on the glass window or door for it to work.

One of the biggest advantages of a shock glass break sensor is that it has fewer instances of false alarms than its acoustic counterparts. However, mounting an individual sensor on each window or glass door makes these sensors generally less affordable than acoustic versions.

Do You Need Glass Break Sensors?

Homeowners who already have motion sensors and door and window sensors installed may wonder if they even need glass break sensors at all. The truth is that motion sensors and door and window sensors are fundamental to your home security system, but glass break sensors form a second line of defense to protect your family, your home, and everything you hold dear from the clutches of criminals.

Relying only on door and window sensors to alert you and your home security monitoring or alarm company to a break-in or burglary can be a foolhardy mistake. For example, if an intruder breaks a window or shatters a glass door, an alarm may not be triggered because the door or window frame is not necessarily disturbed during the event. The bad guy then slips in and does his business undetected.

Add motion sensors to the scenario, and your home is a little better off but not totally out of the woods yet. That’s because a smart thief knows how to avoid motion sensors altogether, remaining unnoticed while gaining entry into your residence.

With glass break sensors installed, the intrusion into your home is detected from the moment the glass shatters.

The FBI notes that bad guys need just 90 seconds to 12 minutes to smash a window and grab what they want. That shocking statistic underscores the need for as many tools in your home security arsenal as possible. Glass break sensors are one of those tools.

Glass break sensors can be invaluable in keeping your home and your family safe and out of harm’s way. These hard-working sensors often foil even the most determined intruder since they frequently identify an attempted break-in before the offender has time to gain a foothold into the home. Even if you have other sensors installed, glass break sensors are another critical component of an effective home security system that gives you the peace of mind that you’re doing everything possible to protect those you love most.

Related: Does An Alarm System Increase Your Home Value?

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