How a Monitored Smoke Detector Works With Your Security System

The Detector Detects Smoke

• Smoke detectors generally have two sensors inside a housing that either have a light beam or an electrical current running between them. When a fire starts, smoke wafts upward and into the chamber of the smoke detector. The smoke particles interrupt the light beam or the electrical current, breaking the connection between the two electrodes. When the connection is broken, the smoke detector will activate. This can also happen as a result of steam or high levels of moisture in the air, since the detector cannot tell the difference between that and actual smoke.

The Detector Notifies the Panel

• The smoke detector is either wired directly into the main control panel for the security system, or it communicates with it through a signal similar to a radio frequency. When the smoke detector activates, the notice of that activation is sent either through the wiring or through the air to the security system control panel, which then interprets the signal to determine the kind of alarm and the exact location of the disturbance.

The Panel Activates the Alarm

• While the smoke detector will likely make its own noise when it detects smoke, the main control panel for the alarm system is hooked up to a siren that will be much louder than the smoke detector by itself. When the control panel is notified of a smoke alarm, it will send a signal to the main siren in much the same way the detector sends a signal to the panel. The siren doesn't have to interpret the signal or determine a location. As soon as it receives a signal of any kind, it will go off to alert the residents in the home of an impending emergency.

Emergency Services Respond to the Alarm

• Many security systems are connected to monitoring companies and to emergency services via the phone line. As a result, the control panel will simultaneously send a distress signal out over the phone line to the monitoring company --- and possibly the fire department as well --- at the same time it activates the main siren of the alarm. The monitoring company will then call the house to try to verify the presence of a fire threat. If the smoke is verified by a resident or if no one answers, the monitoring company will notify the fire department to respond if they aren't already on their way.