What definition fits a door contact in security systems?

A door contact in security systems refers specifically to a sensor that monitors the status of a door, determining whether it is open or closed. This type of device typically consists of two components: a magnet and a switch. When the door is closed, the magnet holds the switch in a position that indicates the door is secure. When the door opens, the magnet moves away from the switch, triggering an alert that the door status has changed.

This function is vital for security systems, as it provides real-time monitoring of entry points. By knowing whether a door is open or closed, security personnel can take appropriate actions based on the status—whether that means enabling alerts, monitoring movements, or engaging response protocols. The effective operation of door contacts is essential in maintaining the integrity of a security system, as they play a direct role in detecting unauthorized access.