How Glass Break Sensors Work

Glass break sensors listen for a specific acoustic signature: the thud of impact followed by high-frequency shattering. Modern dual-frequency sensors reduce false alarms dramatically compared to older models.

One sensor can cover a 15 to 25 foot radius, meaning a single sensor in a living room can monitor multiple windows. They mount on the wall or ceiling, not on the window itself.

How Motion Sensors Work

PIR motion sensors detect changes in heat patterns when a person walks through the detection zone. They are triggered after someone is already inside, making them an interior detection layer, not perimeter defense.

Where to Use Each

Glass break sensors belong in rooms with large ground-floor windows. Motion sensors belong in interior hallways and stairways that an intruder would pass through.

  • Glass break: living room, basement, rooms with large ground-floor windows.
  • Motion: main hallway, top of stairs, room between entry points and bedrooms.
  • Contact sensors on every door and window should come first. They are cheaper and cover the most common entry method.