Complete reference for fire alarm device symbols, circuit types, and control equipment on construction drawings

Fire alarm drawings (FA-series sheets) show the location, wiring, and type of every fire alarm device in a building. While symbols vary between design firms, the devices and general conventions are standardized by NFPA 72 (National Fire Alarm and Signaling Code). These symbols often appear alongside fire protection symbols on life safety plan sheets. Always reference the project-specific legend for exact symbol definitions.

Important: Fire alarm symbols are not standardized across all engineering firms. Always verify device symbols against the project legend on Sheet FA-001 or the first fire alarm plan sheet. For a broader overview of reading these sheets, see our guide on how to read electrical drawings.

Quick Jump

Detection Devices (Initiating Devices)Notification Devices (Alerting Devices)Control Equipment Wiring & Circuits

Detection Devices (Initiating Devices)

Devices that detect fire conditions and send a signal to the fire alarm control panel.

SDSmoke Detector (Photoelectric)

Detects visible smoke particles using light scattering. Most common type in commercial buildings.

Typical Placement:Ceiling-mounted, max 30' spacing per NFPA 72

SD-ISmoke Detector (Ionization)

Detects invisible combustion particles. Better for fast-flaming fires. Less common due to nuisance alarms.

Typical Placement:Ceiling-mounted, max 30' spacing

SD-DDuct Smoke Detector

Mounted in HVAC ductwork to detect smoke in the air handling system. Triggers fan shutdown.

Typical Placement:In supply ducts serving 2,000+ CFM per IMC

SD-BBeam Smoke Detector

Projected beam across large open spaces. Transmitter on one wall, receiver on opposite wall.

Typical Placement:High-ceiling spaces (warehouses, atriums) over 30'

HDHeat Detector (Fixed Temp)

Activates at a preset temperature (typically 135°F or 200°F). Used where smoke detectors would false alarm.

Typical Placement:Kitchens, garages, mechanical rooms, loading docks

HD-RORHeat Detector (Rate of Rise)

Activates when temperature rises faster than 15°F per minute. Also has fixed-temp backup.

Typical Placement:Areas needing fast detection without smoke detector sensitivity

FPSManual Pull Station

Manual fire alarm activation device. Pulled by occupants to initiate building alarm.

Typical Placement:Within 5' of each exit, max 200' travel distance, 42-48" AFF

WFWaterflow Switch

Detects water flow in sprinkler piping. Sends alarm signal when sprinklers activate.

Typical Placement:On each sprinkler riser and floor control valve assembly

TSTamper Switch

Monitors valve position. Sends supervisory signal if a sprinkler valve is partially or fully closed.

Typical Placement:On every control valve in the sprinkler system

Notification Devices (Alerting Devices)

Devices that alert building occupants to evacuate or take action during a fire alarm.

H/SHorn/Strobe Combination

Combined audible (horn) and visual (strobe) notification. Most common notification device in commercial buildings.

Typical Placement:Per NFPA 72 — max 50' x 50' rooms for strobes; 15 dBA above ambient for horns

HHorn (Audible Only)

Audible notification only. Used where visual notification is provided separately.

Typical Placement:Must achieve 15 dBA above ambient or 5 dBA above max sound level

SStrobe (Visual Only)

Visual notification for hearing-impaired occupants. Required in public and common areas.

Typical Placement:ADA requirement: corridors max 100' spacing, 80-110" AFF mounting height

SPKSpeaker

Voice evacuation speaker. Provides pre-recorded and live voice announcements during emergencies.

Typical Placement:Replaces or supplements horns in high-rise, assembly, and healthcare occupancies

SPK/SSpeaker/Strobe

Combined voice speaker and visual strobe notification device.

Typical Placement:High-rise buildings, hospitals, large assembly spaces

CHMChime

Gentle tone notification for non-emergency alerts or pre-alarm conditions.

Typical Placement:Healthcare facilities for staff notification (Code Blue, etc.)

Control Equipment

Central equipment that monitors, controls, and communicates fire alarm system status.

FACPFire Alarm Control Panel

The brain of the fire alarm system. Receives signals from initiating devices, activates notification devices, and communicates with monitoring station.

Typical Placement:Near main entrance in fire command center or electrical room

FAACPFire Alarm Annunciator Panel

Remote display panel showing system status and zone information. Located where fire department enters the building.

Typical Placement:Main entrance, fire command center

NACNAC Power Extender

Notification Appliance Circuit booster panel. Provides additional power for notification devices on large systems.

Typical Placement:Electrical rooms on remote floors or wings

DACTDigital Alarm Communicator

Transmits alarm signals to the central monitoring station via phone lines or internet.

Typical Placement:Integrated into or adjacent to FACP

RMMRelay Module

Controls auxiliary functions: elevator recall, door hold-open release, HVAC shutdown, stairwell pressurization.

Typical Placement:At controlled equipment location

MONMonitor Module

Monitors conventional (non-addressable) devices and connects them to an addressable system.

Typical Placement:At device location or in junction box

Wiring & Circuits

Line types and circuit designations used on fire alarm drawings.

SLCSignaling Line Circuit

Addressable communication circuit connecting initiating and monitoring devices to the FACP. Class A (looped) or Class B (single run).

Typical Placement:Between FACP and all addressable devices

NACNotification Appliance Circuit

Power circuit from FACP to notification devices (horns, strobes, speakers). Carries 24VDC power.

Typical Placement:Between FACP/NAC panel and notification devices

IDCInitiating Device Circuit

Conventional (non-addressable) circuit connecting initiating devices. Used in smaller systems.

Typical Placement:Between FACP and conventional detectors/pull stations

EOLEnd of Line Resistor

Supervision resistor at the end of each circuit. Allows FACP to detect open or short circuit faults.

Typical Placement:At the last device on each IDC or NAC circuit

Key Coordination Points

Duct detectors require coordination with mechanical — verify duct sizes and detector access panel locations

Strobe candela ratings depend on room size — verify room dimensions match the specified candela on the schedule

Elevator recall devices must be coordinated with the elevator contractor and comply with ASME A17.1

Door hold-open devices require both fire alarm and architectural coordination for fire-rated door assemblies

HVAC shutdown on alarm must be coordinated with the mechanical engineer and BAS contractor

Speaker/strobe locations must avoid conflicts with lighting fixtures, HVAC diffusers, and structural members — see our reflected ceiling plan coordination guide for more

Related Resources

Fire Protection Symbols Guide

Sprinkler, standpipe, and suppression system symbols.

Fire Rating Pattern Guide

Line types for fire walls, barriers, and smoke partitions.

How to Read Electrical Drawings

Fire alarm is often on the E-sheets.

Fire Protection Drawing Review

Best practices for reviewing fire protection plans.

Fire & Life Safety Analysis

Automate fire alarm coordination checks with AI.

Electrical Abbreviations Guide

Abbreviations used alongside fire alarm drawings.

Review Fire Alarm Plans Faster

Articulate's AI helps identify fire alarm coordination issues — missing devices, incorrect spacing, duct detector conflicts, and coverage gaps — during automated drawing review.

Try Automated Drawing Review

Sources

NFPA 72 — National Fire Alarm and Signaling Code, 2025 Edition

NFPA 101 — Life Safety Code

ADA Standards for Accessible Design — Visual Alarm Requirements

Fire Alarm Symbols Guide