Modern home security is an electronics-heavy environment dominated by technologically advanced sensors. Everything from motion detectors to video cameras operates using sensors as triggers. But some 50 years ago, when what we now know as modern home security was first born, perimeter sensors were the only game in town. They were, and still are, the foundation of modern security technology.
Perimeter sensors are also known by two other names: entry and contact sensors. They are the first line of defense in any electronic home security system. If you were to buy an entry-level system from a provider like Vivint Home Security, the system would include at least a few perimeter sensors.
Perimeter Sensors: What They Are
Perimeter sensors are essentially triggers. They define the boundary between authorized and unauthorized spaces. When an unauthorized person attempts to enter the protected space of a home’s interior, a perimeter sensor triggers an alert.
At their core, perimeter sensors are electromechanical devices. Most modern home security systems utilize magnetic contact sensors to protect the perimeter. They are typically attached to first-floor windows and doors, though they can also be attached to gates, fences, etc.
Each contact sensor has two components that make it work:
- The Switch – The switch is contained in a small housing mounted on either the door or window frame. Inside is a spring-loaded metal connector.
- The Magnet – A magnet is housed in the piece installed on the opposing surface. The housing also contains a second metal connector.
Most installations put the magnet housing on the moving surface. That would place it on the door or window, with the switch being mounted on the door or window frame. It is simple technology that has proven itself over decades of use. In this particular case, simple is good.
How Perimeter Sensors Trigger Alarms
Based on the above description, you might already know how perimeter sensors trigger alarms. I will explain it, nonetheless. Perimeter sensors have two states: normal and active. In the normal position, the two pieces maintain contact via the magnet in the one housing pulling the two metal connectors together. The normal state can only be achieved when the door or window is closed.
The two metal connectors being joined together completes an electrical circuit. It is what tells the security system’s central hub that the sensor is in its normal state. In the active state, however, the two connectors are pulled apart because the door or window is opened. This breaks the electrical circuit, alerting the system to the fact that contact has been broken.
The system interprets a broken contact as unauthorized entry. It then sounds an alarm and sends an alert to either the user’s smartphone or a remote monitoring center.
Immediate Notification
Even though modern home security systems tend to be equipped with video surveillance cameras and other more advanced devices, the perimeter sensor continues to be a fundamental component in every system. Its value rests in its immediate notification capabilities.
Motion sensors can lag. They are also known for their blind spots. Likewise, cameras do not always pick up potential criminal activity at the earliest possible stages. The benefit of the perimeter sensor is that it activates a warning the very second contact is broken. No other device in a home security system works us quickly as a perimeter sensor.
As simple as perimeter sensors are in their function, they are still the foundation of an effective home security system. They are so effective that no competent home security provider would offer a system void of any perimeter sensors. They are just that important.