#TrellidorAnswers: What Are Security Door Contacts?

Different features and devices all form part of home security systems to create robust layers of protection. One of the common security systems elements include security door contacts. With our aim to provide informative responses to your frequently asked questions, let’s quickly delve into what security door contacts are.

Doors and windows are common entry and exit points in any building – making them crucial components to mark and protect first in any security blueprint plan. A lot of devices have been created with this sole purpose in mind, such as security door contacts. A security door contact is a device consisting of a sensor and a magnet.

If the device is surface-mounted, then the sensor and magnet get installed on the surface of the door and its frame. Should the sensor be recessed, then the sensor and magnet get inserted into holes that are drilled into the door and its frame. The standard practice is to have the sensor on or inside the door frame, while the magnet is on or inside the door itself.

The aim with a door contact is to align the sensor properly with the magnet so that the two are in direct contact when the door is closed. This is the reason why these sensors are called “door contacts”. Opening the door causes the magnet to become separated from the sensor, releasing a metal reed switch from inside the sensor. The sensor then recognizes this and reports the change in status to the alarm control panel.

Why Do I Need Security Door Contacts?

  • Activate Alarms

Contacts are used in security systems to trigger alarms if an intrusion is detected. Should a sensor transmit ‘open’ window or door signals in an armed security system, the alarm is set off.

  • Offer Protection

Being alerted& having the alarm sound off when intrusion is detected not only startles&scares off burglars, but it also gives home occupants a chance to take safety measures.  Given the ease of installation and wireless nature of security door contacts, they can also be attached to assets. Homeowners will be able to keep track of any valuables such as jewellery boxes and safes – letting them know when these are opened or accessed.

  • Integrates & Activates Devices in the same Security Systems

In addition to activating and transmitting alerts, security door contacts can automatically trigger or activate various devices within existing home security systems. The sensors send real-time data into the system to activate other connected devices. For example, if a yard gate is opened at night, contact sensors are able to turn on the outside lights. They can trigger automatic thermostat set back if they detect open windows and doors. Door contacts may also be used as door bells.

Types of Security Door Contacts

  • Overhead Door Contact Sensors
  • Roller Ball Door Contact Sensors
  • Surface-Mount Door Contact Sensors
  • Pull Apart Contact Sensors
  • Recessed Door Contact Sensors

In our other edition of our Frequently Asked Questions, see #TrellidorAnswers: What Are The Best Burglar Bars?


Alarm Grid. (2019). What Is a Security Door Contact? – Alarm Grid. [online] Available at: What Is a Security Door Contact?[Accessed 28 Nov. 2019].

Alarm Grid. (2019). What Are Door Contacts?. [online] Available at: What Are Door Contacts? [Accessed 28 Nov. 2019].

Getkisi.com. (2019). Door Contact Sensor Alarm | Kisi. [online] Available at:  Door Contact Sensor Alarm [Accessed 28 Nov. 2019].


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