Door and window detector

A door and window detector is the part of an alarm system that gives the signal when a door, a window or a roller shutter that should be closed is opened.

It is fitted to the frame and to the door or window leaf, and it is most often a magnetic contact: while the two parts are together nothing happens, and when they separate the alarm detects it. Unlike a motion detector, it gives the alert at the moment the way in is opened, before the person is inside.

The most common faults are false alarms caused by a door that does not close properly or a window that rattles in the wind, and detectors that stop working because of the battery or damp.

A detector gives the alert, but it does not stop anyone. If the door opens easily, it is worth reinforcing it first. We explain it on our security upgrades page.