Glass break sensors often come as standard with car alarms in New Zealand.
As the name suggests, they are designed to detect if a window has been smashed.
Most are little more than a glorified microphone that detects high pitch sound and in turn, triggers the alarm.
Normally they are installed in the front area of a vehicle, either below the dashboard or above it.
Why Glass Break Sensors are not very effective
One of the weak points of a glass break sensor is that they are not very effective in large vehicles.
For example, a sensor fitted in the front of a van is unlikely to detect sound in the back, let alone protect against a sliding window being removed.
They are also not recommended for vehicles where window tint film is fitted.
Pillarless windows and window tint film both stop glass break sensors being effective
Pillarless windows can me pulled open to access the cabin without smashing the glass.
Window tint film changes the acoustic sound of the glass breaking, The sensor is designed to detect a high pitch shattering sound. The film muffles the sound of the glass breaking.
Glass break sensors can also cause a false alarm if the sensitivity is set to high. The materials inside a car can cause a creaking sound as they expand and contract with a change of temperature which can be enough to trigger an overly sensitive sensor.
Ultrasonic sensors are a far more effective and reliable way of protecting the internal space in a vehicle and would be my choice over a glass break sensor every time.
Thatcham approved alarms (CAT 1 and CAT 2-1) require movement detection, such as ultrasonic sensors or a microwave sensor, so glass break sensors are not approved under these standards as it is known that they may not work.
