A smoke detector is a device that senses smoke, typically as an indicator of fire. An addressable system gives each detector an individual number, or address. Addressable systems allow the exact location of an alarm to be plotted on the FACP. In certain systems, a graphical representation of the building is provided on the screen of the FACP which shows the locations of all of the detectors in the building, while in others the address and location of the detector or detectors in alarm are simply indicated.
Analog addressable systems are usually more expensive than conventional non-addressable systems,and offer extra options, including a custom level of sensitivity (sometimes called Day/Night mode) which can determine the amount of smoke in a given area and contamination detection from the FACP that allows determination of a wide range of faults in detection capabilities of smoke detectors. Detectors become contaminated usually as a result of the build up of atmospheric particulates in the detectors being circulated by the heating and air-conditioning systems in buildings. Other causes include carpentry, sanding, painting, and smoke in the event of a fire. Panels can also be interconnected to control a very large number of detectors in multiple buildings. This is most commonly used in hospitals, universities, resorts and other large centers or institutions.