The basic function of a Fire Alarm System is to detect a fire and alert the occupants so that they must leave the building. It consists of several different devices – a control panel, automatic fire detection devices, manual devices and alerting devices, each strategically located for efficiency.

The Control Panel is the central processor of the system. It produces two different outputs, an Alarm and a Trouble. It takes signals from the automatic and manual fire detection devices and causes an alarm by operating the alerting devices throughout the building. It monitors the wiring, the devices, the batteries, and the commercial electricity for faults which limit the capability of the system and causes a trouble by operating audible and visual indicators on its front panel.

Smoke Detectors and Heat Detectors are automatic fire detection devices that can detect a fire condition when the fire has the right signature for the device, e.g., smoke is required to trigger a smoke detector and a heat detector goes off when the temperature rises at a fast or to a certain degree. A Pull Station is a manual alarm device which a person, who has noticed a fire before a smoke or heat detector operates, can pull when leaving the building. Bells, horns, chimes, speakers and strobes are alerting devices which are triggered by the control panel to alert those present that a fire condition has been found and that they should leave the building.

In addition, capabilities can be added to the fire alarm system to contact the fire department, fan shut down, close doors and unlock doors in the event of a fire being detected.