What Is a Security Door Contact?

A security door contact is usually a device consisting of a sensor and a magnet that is attached to a door and its frame. When the door is opened, and the magnet separates from the sensor a signal is sent to the panel. This lets the security system know that the door has been opened.

Wired door contacts are very simple devices. They work by providing either a closed circuit, or an open circuit, depending on the state of the door being protected. With wired contacts, all the processing is done by the alarm panel to which the contacts are connected. Multiple door contacts can be connected to a single hard wired zone.

Wireless door contacts work by being assigned to a zone on the security panel. When the door is opened, the sensor recognizes that the magnet has been removed, causing the contact to send a "fault" message to the alarm panel. With wireless zones, all the processing takes place within the contact itself. If the system is in an armed state when the "fault" occurs, an alarm may be triggered. If the zone is programmed as perimeter, the alarm will be instant, if the door is programmed as an Entry/Exit zone, the system must be disarmed within the specified delay time to prevent an alarm.

In order for the security system to recognize the door contact, the device will need to be programmed with the panel. This process varies depending upon what type of panel the user has and whether the door contact is wired or wireless. Once the sensor has been programmed, it can then be installed on the door.

When mounting the device, it is recommended that the magnet be placed on the moving part of the door and the sensor itself on the door frame. By mounting the sensor on the door frame, it will be less likely to become damaged when the door is opened and closed. Security door contacts can be used with almost any type of door, including French doors and sliding doors.

In addition to surface-mounted contacts, there are also recessed door contacts that will make the device less-visible on the door. Recessed door contacts can be desirable when appearance is an issue. However, recessed door contacts are typically more difficult to install, and they will usually require that holes be drilled into the door and the door frame.