Bypass glass break sensors

Glass-break sensors are available in a variety of shapes and sizes. Here are the most common methods of detecting glass breakage.
Audio glass-break sensors are placed in a room next to the area to be protected. They are designed to hear the high-pitched sound of shattering glass. Some units are sensitive enough to cover an entire bank of windows. The disadvantage of using this type of device is that if it is too sensitive, it could hear a noise that may sound like glass breaking and activate the alarm. Since most of these devices have adjustments built into them, you’ll want to test the sensitivity carefully.
In a home, the only protection that is normally used are contact switches attached to the doors and windows and possibly a motion detector in a high-traffic location. Up to this point we have not done anything to physically protect the glass. You can add a motion detector to each room of your home, but due to the cost and inconvenience, that probably isn’t a good option.
The audio glass-break sensor is better because it is relatively inexpensive and won’t restrict movement in the home the way a motion detector will. Audio glass-break sensors are used to protect businesses too.
Shock sensors are placed on the actual metal frame of a window and are designed to detect the shock of intrusion through that particular opening. There are some new models that act as combination shock sensors and audio units. They, come in various sizes, from as small as a quarter up to the size of a half a pack of cigarettes.
Shock sensors are mostly used in businesses and are mounted directly on the metal frame of a bank of windows. On the picture below you can see where the sensor is located on a typical storefront window. See if you can spot them the next time you are running errands.

The circumvention technique used on shock sensors is the same as with other motion-detection equipment. The two wires that connect to the alarm loop need to be removed from the device and twisted. That will prevent the unit from being detected on the alarm loop and sending the signal back to the master control.
Window foil is another widely used device to detect glass breakage. You’ve all seen this stuff. It looks like silver metal tape that is applied to the doors and windows of commercial buildings. For example, a glass door or window protected with foil.
The foil is designed to go around the perimeter of the window, and it is always applied on the inside of the glass. The theory here is simple. The foil acts as if it were a wire protecting the window. When the window is smashed, the foil is broken by the falling glass. Because it is so thin, it breaks very easily. The flow of power is cut off to the alarm master control and the alarm system activates.
This is obviously so simple that you probably are wondering why every alarm company doesn’t use it. For starters, it’s very old technology. It is also troublesome by nature. It is also very easy to circumvent.
What are some of the problems with window foil? Since it is so thin, window washers can and do tear it very easily. When that happens, the alarm service person needs to stop by and do what is called a foil repair, which is really just patching up the tear in the foil. It does have a protective coating on it, but as it ages this coating disappears. Another problem is as the weather changes, the glass contracts and expands slightly. In cold weather it tends to expand and in the heat it contracts. After time, this movement can make small cracks in the window foil, which in turn causes high resistance in the alarm circuit and creates false alarms.
Because of these service problems, foil is not used much anymore on new installations. There are still, however, thousands of windows protected by it.
The circumvention technique for window foil is so simple anyone could do it! Please see the illustration.

Bypass the foil – the technique here is almost the same as the others. The goal is to bypass the protection device. As you can see, both ends of the foil are connected to the alarm protection loop. What we do is remove the wires from both sides and twist them together. That’s it! The window foil is now out of the protection loop and not capable of sending signals back to the alarm master control because it is now considered to be bypassed, as shown in the pictures above.

The lesson learned here is that, when designing a security system for your home or business, the placement of detection devices is very important. They need to be placed in an unobstructable area and walk-tested regularly to insure their proper operation. If the motion detectors are walk-tested with the alarm control in the test position, you’ll know that they are connected properly to the protection loop and no one has disconnected them because the signals will be acknowledged by the alarm master control. If someone has circumvented the protection loop, the detection signals will not be registering at the master control.
As you noticed while you read through this, almost all of the circumvention techniques are very similar. Contact switches, motion detectors, and other detections devices can be bypassed by simply twisting two wires together. I’m sure you now have a nice secure feeling about your alarm system. Yeah, right! Once again, my purpose in writing this book is not necessarily to show you how to defeat alarm systems but to show you how to protect yourself and your valuables properly.

If you want to learn more (really learn, not just read about), get these 2 books!

Bypass glass break sensors

Techniques of Burglar Alarm Bypassing

Defeating Burglar Alarms: How They Work, and How Burglars Bypass Them

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