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Door Sensors in a Security System

Posted by Alexa Sandbakken on Nov 21, 2014 1:28:00 PM

Technician Terry installs a wireless door sensor

Also called a door position switch, door sensors monitor if a door is opened or closed. But how?

Many door sensors use a magnet to determine the position of the door. This magnet is often placed at the top of the door. Inside each door sensor is a read switch, or two metal pieces, inside a glass tube. When the magnet is in proximity to the read switch, the metals in the switch touch, and the security loop shows the door as closed.


Wired Door Sensors

These sensors are inside the door frame and connect with a magnet on the door. A house must be pre-wired in order to use these sensors.

picture of a wireless door sensor

Wireless Door Sensors

These sensors are more common and appear outside a door and frame. Wireless door sensors may wear out if a door is slammed frequently (loosening the solder joints). Regular use of the door over time can also cause parts of the sensor to work differently than they should. For example, if the glass tube containing the read switch gets cracked or the door warps, false alarms can occur more frequently.

For more information about the differences between wired and wireless security systems, see this blog post or download our security system resource guide.


Door sensors in a security system are a common way to help protect your home from intruders. Regular maintenance of wireless door sensors will keep them in tip-top shape. For more information about door sensors and other features in a security system, contact us!

Updated March 10, 2016

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