Initiating devices provide an input to the fire alarm control unit.

Manual and Automatic

There are many types of initiating devices used on building fire alarm systems All of them can be classified as either manual or automatic.The most common manual initiating device is the fire alarm box, which many people refer to as a pull station, Automatic initiating devices include, heat detectors, smoke detectors, radiant energy-sensing fire detectors and gas detectors. These initiating devices are designed to automatically sense some type of environmental condition and to automatically signal the control unit.

Conventional and Addressable

initiating devices can be classified as being either conventional or addressable. Conventional initiating devices operate like switches. With conventional initiating devices, the fire alarm control unit does not know which device is on. The panel can only tell that some initiating device on a particular circuit has been activated.

Addressable initiating devices have two-way communication with the fire alarm control unit. This allows them to communicate their status to the fire alarm control unit and convey exactly which device has been turned on.

alarm and supervisory signal initiating devices.

initiating devices are being either alarm initiating devices or supervisory signal initiating devices.

For example, smoke detectors almost always are used to initiate an alarm response on a fire alarm control unit. but, sprinkler valves tamper switches usually initiate a supervisory signal on the fire alarm control unit.