A conventional fire alarm system operates by dividing the premises into distinct zones, each equipped with a set of fire detection devices, such as smoke detectors, heat sensors, and manual call points. When an alarm is triggered, the fire alarm control panel can identify the specific zone in which the activation occurred, but it does not provide information about the exact location or individual detector that was triggered.

The system uses a series of interconnected wiring that links all devices within a zone back to the control panel. To complete the circuit and ensure proper signaling, a terminal or end-of-line device, such as a resistor, is installed at the end of each zone. This component helps return current from one pole to another, ensuring that the system detects any breaks or faults in the wiring and triggers an alarm if necessary.