What is a Magnetic Contact?

A magnetic contact is a door and window sensor that functions using an internal reed switch in conjunction with a magnet. This is the most common way for a door and window sensor to operate. These devices are known for being particularly easy to use and enroll with security systems.

Like the name implies, a door and window sensor is used to monitor a door or a window and let an alarm system know when it has been opened. These devices are sometimes referred to as "magnetic contacts" because of the way that they operate. While not every door and window sensor functions in the same manner, the majority of these devices operate using the same principles.

The typical door and window sensor consists of a sensor with an internal reed switch and a separate magnet. The sensor is usually installed on the door or window frame, and the magnet is installed on the moving portion of the door or window. For best results, the magnet should be placed within about a half-inch of the sensor. When the door or window is opened, the magnet will separate from the sensor.

Once this happens, the sensor's internal reed switch will activate. In the case of a wireless zone, this will tell the sensor to send an alert to the alarm system to let it know that the door or window has been opened. In the event of a wired zone, this process will actually open a wired circuit which indicates to the system the door or window has been opened. The system will then perform a predetermined action based on the programming settings for the sensor. So as long the sensor remains in contact with its magnet, the device won't send an alert to the alarm system.

Both wired and wireless door and window contacts are available for security systems. Both types generally operate using the same aforementioned principles. Remember, a wireless door and window contact will need to communicate at a wireless frequency that is compatible with the alarm system being used.