Home Insurance Guide

So the security system you had installed comes with several window and door sensors and you’re curious how they work. Understanding how they work can also pay dividends down the road when you start troubleshooting if your security system ever gives you problems, such as false alarms from a sensor or “zone.”

There are basically two types of sensors but each works on the same principle, that of a flowing electrical charge. A closed-circuit system is one in which the electrical charge is permitted to flow when the window or door is closed, when the contacts touch they permit an electrical charge to pass through and “close” the circuit. An open-circuit system is just the reverse, the circuit is broken when the door or window is closed. Inside the sensor is a magnet that is either of the same polarization or the opposite polarization of the other magnet, thus pushing or pulling the contacts inside of the sensor together; breaking or making the connection.

Now, if the system is alarmed and there is a change in the condition of the system or a zone, the security system will trip and the alarm will sound. If there was no control box and the sensor were directly hooked up into an alarm, the alarm would be deactivated as soon as the burglar shut the door or window!