The word “conventional” is used to distinguish the method used to communicate with the control unit in newer addressable systems. So called “conventional detectors” are smoke detectors used in older interconnected systems and resemble electrical switches in their information capacity. These detectors are connected in parallel to the signaling path so that the current flow is monitored to indicate a closure of the circuit path by any connected detector when smoke or other similar environmental stimulus sufficiently influences any detector.
The resulting increase in current flow is interpreted and processed by the control unit as a confirmation of the presence of smoke and a fire alarm signal is generated. In a conventional system, multiple smoke detectors are typically wired together in each zone and a single fire alarm control panel usually monitors a number of zones which can be arranged to correspond to different areas of a building.
In the event of a fire, the control panel is able to identify which zone or zones contain the detector or detectors in alarm, but cannot identify which individual detector or detectors are in a state of alarm.