Fire Alarm System Fundamentals and Definitions
Domain 1 covers the vocabulary and architecture the exam uses in every later question. You must distinguish a fire alarm system from a detection system, identify the signal types, and know how conventional and addressable systems differ.
Core concepts
- A fire alarm system includes initiating devices, notification appliances, a control unit, power supplies, and the circuits connecting them. A detection system may have no notification appliances.
- Three operational signal types: alarm (fire or waterflow), supervisory (valve tamper, low air pressure, pump running), and trouble (open circuit, ground fault, battery failure).
- Conventional systems use zones; an alarm identifies the zone, not the individual device. Addressable systems give each device an address on a Signaling Line Circuit, so the panel annunciates the specific device.
- Initiating devices include manual pull stations, smoke and heat detectors, duct detectors, and waterflow switches. Notification appliances include horns, strobes, and speakers.
- The supervising station monitors the protected premises; the protected premises is the building being monitored.
Worked example
A sprinkler riser has a waterflow switch and a valve tamper switch. The waterflow switch is an initiating device and produces an alarm signal. The tamper switch produces a supervisory signal, not a trouble. A break in the circuit to the tamper switch is a trouble. This distinction matters because alarm, supervisory, and trouble signals have different annunciation and response requirements.
Traps
- Calling a valve tamper an alarm.
- Treating a ground fault as a supervisory condition.
- Assuming addressable means wireless.
- Forgetting that waterflow is an alarm-initiating input and that duct detectors are initiating devices.