Fire Alarm Glossary

The central controller of a fire alarm system. It monitors devices, processes events, and controls notification appliances. Service and programming must be performed by licensed fire alarm technicians.

Each device has a unique address so the panel can pinpoint the exact device in alarm or trouble.

Devices are grouped by zones; the panel indicates which zone is in alarm rather than the exact device.

Remote display that shows system status and events for responders, often near main entrances.

The component of the fire panel that dials out to a central monitoring station over phone lines to report alarms, troubles, and supervisory signals.

Circuit that powers and supervises notification appliances such as horns, strobes, and speakers. A NAC trouble indicates a fault that needs professional service.

Communication circuit for addressable devices. Device missing or open circuit messages usually indicate wiring or device issues that a licensed technician should diagnose.

Conventional zone wiring for pull stations and detectors on non-addressable systems.

A resistor placed at the end of a conventional circuit (NAC or IDC) to allow the panel to supervise the wiring for open circuits.

Wiring methods for fire alarm circuits. Class B uses a single pair of wires with an end-of-line resistor. Class A uses a redundant return path to the panel, allowing the circuit to function even if a wire breaks.

A trouble condition where a circuit wire accidentally touches earth ground (conduit or metal box), which can interfere with system communication and must be located and cleared.

Manual device to activate the fire alarm; typically located near exits and in corridors.

Combined audible (horn) and visible (strobe) notification appliance for occupant alerting.

Notification appliance that delivers voice evacuation messages along with a strobe for visibility.

Detects high temperatures (Fixed Temp) or rapid temperature rise (Rate-of-Rise). Used in areas too dusty or steamy for smoke detectors, like kitchens or mechanical rooms.

Detects smoke in HVAC ducts and often shuts down fans to prevent smoke spread.

A smoke detector that projects a beam of light across a large open space (like a gym or warehouse) to a reflector or receiver. Smoke obscuring the beam triggers the alarm.

Detects carbon monoxide and uses a different temporal pattern than fire alarms.

An addressable interface module used to monitor conventional contacts, such as waterflow switches, tamper switches, or conventional pull stations.

An addressable output module used to switch power or control external equipment like door holders, elevators, or HVAC dampers.

A system fault such as wiring, power, or device issues that requires service.

Off-normal condition of fire protection equipment (for example, a closed sprinkler valve) that needs attention.

Standard alarm sound patterns: T-3 for fire evacuation and T-4 for carbon monoxide alarms.

A system that uses speakers and amplifiers to broadcast spoken instructions during an emergency, which is more effective than simple sirens for guiding occupants.

Detects water movement in a sprinkler system and typically triggers a fire alarm signal.

Monitors sprinkler control valve position; a change triggers a supervisory condition.

Local authority that enforces fire and life safety codes and approves installations.

The standard published by the National Fire Protection Association that governs the application, installation, location, performance, and inspection of fire alarm systems.