Fire Safety Glossary
Comprehensive fire safety terminology explained in plain language. From technical specifications to industry acronyms.
Addressable System
A fire alarm system where each device has a unique address, allowing the control panel to identify exactly which device is activated. Provides precise location information for faster emergency response.
AHJ (Authority Having Jurisdiction)
The organization, office, or individual responsible for enforcing fire codes and approving fire protection systems. Could be the fire marshal, building inspector, or other local authority.
Alarm Verification
A feature that requires a smoke detector to sense smoke for a minimum period or receive multiple activations before triggering an alarm. Reduces false alarms from transient smoke.
Aspirating Smoke Detection
A highly sensitive smoke detection method that continuously draws air samples through a pipe network to a central detector. Brand name examples include VESDA and FAAST. Used in high-value or sensitive areas.
Audible Notification Device
A device that produces sound to alert building occupants of a fire alarm. Includes horns, bells, chimes, and speakers. Must meet minimum sound level requirements (typically 75-85 dB).
Beam Detector
A smoke detector that projects an infrared beam across a protected area. When smoke obscures the beam, an alarm is triggered. Ideal for high-ceiling spaces like warehouses and atriums.
Battery Backup
Secondary power source (typically batteries) that operates the fire alarm system when main power fails. Most codes require 24-72 hours of standby power plus alarm duration.
BACnet
Building Automation and Control Networks - a communication protocol used to integrate fire alarm systems with building management systems (BMS) for centralized monitoring and control.
CE Marking
European conformity marking indicating a product meets EU health, safety, and environmental requirements. For smoke detectors, requires EN 14604 certification by a Notified Body.
Central Station
A facility that receives fire alarm signals from protected premises and dispatches emergency services. Must be listed by a recognized testing laboratory and staffed 24/7.
Conventional System
A fire alarm system that groups devices into zones. When activated, the panel identifies the zone but not the specific device. Less expensive but provides less precise location information than addressable systems.
Cross-Zoning
Requiring two detectors in the same area to activate before triggering an alarm or suppression system. Reduces false alarms in sensitive applications.
Duct Detector
A smoke detector designed to sample air from HVAC ducts. Detects smoke in air handling systems and can shut down fans to prevent smoke spread throughout a building.
Dual-Sensor Detector
A smoke detector combining both ionization and photoelectric technologies in one unit. Provides faster response to both fast-flaming and slow-smoldering fires.
EN 14604
European standard specifying requirements for smoke alarm devices. Covers sensitivity, alarm sound output, battery life, environmental resistance, and marking requirements. Mandatory for CE marking in Europe.
EN 54
European standard series for fire detection and alarm systems. EN 54-7 covers smoke detectors for system use, while EN 54-5 covers heat detectors.
End-of-Line (EOL) Device
A resistor or other component installed at the end of a supervised circuit. Allows the control panel to detect wiring problems like open or short circuits.
Evacuation Signal
The audible and/or visible signal that indicates occupants should leave the building. Modern codes require a specific temporal pattern (three pulses, pause, repeat).
False Alarm
An alarm activation caused by something other than a fire, such as cooking smoke, steam, dust, or equipment malfunction. False alarms waste emergency resources and can lead to alarm fatigue.
Fire Alarm Control Panel (FACP)
The central component of a fire alarm system that monitors inputs (detectors, pull stations), controls outputs (notification devices), and communicates with monitoring services.
Flame Detector
A detector that responds to electromagnetic radiation (UV, IR, or both) emitted by flames. Used in high-hazard areas where rapid flame detection is critical.
Gateway
In wireless fire alarm systems, a device that receives signals from wireless detectors and communicates with the control panel or cloud platform. Also called a bridge or hub.
General Alarm
An alarm condition where all notification devices in a building are activated, indicating all occupants should evacuate.
Heat Detector
A fire detection device that responds to temperature. Fixed-temperature types activate at a specific temperature (typically 135°F/57°C or 200°F/93°C). Rate-of-rise types activate when temperature increases rapidly.
Horn/Strobe
A notification device combining an audible horn and visible strobe light. Strobes are required for ADA compliance to alert hearing-impaired occupants.
Initiating Device
Any device that initiates an alarm signal, including smoke detectors, heat detectors, manual pull stations, and water flow switches.
Ionization Smoke Detector
A smoke detector that uses a small amount of radioactive material to ionize air. Smoke particles disrupt the ionization current, triggering an alarm. Best for fast-flaming fires.
Interconnected
Smoke detectors that are linked together so that when one activates, all units sound the alarm. Can be connected by wire or wireless radio frequency.
Linear Heat Detection
A cable-type heat detector that can sense temperature changes along its entire length. Used to protect cable trays, conveyors, and other linear hazards.
Listed
Equipment that has been tested and certified by a recognized testing laboratory (such as UL or FM) to meet applicable standards and is suitable for a specific purpose.
LoRaWAN
Long Range Wide Area Network - a low-power, long-range wireless protocol used in IoT fire detection systems. Enables battery life of 10+ years and communication range of several kilometers.
Manual Pull Station
A wall-mounted device that allows building occupants to manually initiate a fire alarm by pulling down a handle. Must be located at exits and along exit routes.
Mass Notification System (MNS)
A system that provides real-time information and instructions during emergencies, including fire, severe weather, or security threats. May include voice messages, text displays, and building-wide announcements.
Monitoring
The process of transmitting fire alarm signals to a central station or other monitoring location where appropriate response actions are initiated.
NAC (Notification Appliance Circuit)
The wiring circuit that powers and controls notification devices (horns, strobes) in a fire alarm system.
NFPA
National Fire Protection Association - an organization that develops fire safety codes and standards, including NFPA 72 (National Fire Alarm Code) and NFPA 101 (Life Safety Code).
Notified Body
An organization designated by an EU member state to assess product conformity with European standards. For smoke detectors, Notified Bodies conduct EN 14604 testing and certification.
Nuisance Alarm
See False Alarm. An unwanted alarm caused by non-fire sources.
Obscuration
The reduction of light transmission caused by smoke particles. Measured in percent per foot or percent per meter. Used to specify smoke detector sensitivity.
OEM (Original Equipment Manufacturer)
A company that manufactures products that are sold under another companys brand name. In fire alarms, OEM services include custom branding and packaging.
ODM (Original Design Manufacturer)
A company that designs and manufactures products that are rebranded and sold by other companies. May include custom design and engineering services.
Photoelectric Smoke Detector
A smoke detector that uses a light source and photosensitive sensor. Smoke particles scatter light onto the sensor, triggering an alarm. Best for slow-smoldering fires.
Pre-Action System
A type of fire suppression system that requires two events (detector activation and sprinkler head opening) before water is released. Used to protect water-sensitive equipment.
Primary Power
The main electrical supply to a fire alarm system, typically from the buildings electrical service. Must have dedicated circuit and be supervised for power failure.
Rate-of-Rise Detector
A heat detector that activates when temperature rises faster than a specified rate (typically 15°F/minute). More responsive than fixed-temperature detectors for fast-developing fires.
Remote Annunciator
A panel located away from the main fire alarm control panel that displays system status and alarm information. Often located at building entrances for firefighter access.
SLC (Signaling Line Circuit)
The communication circuit between the fire alarm control panel and addressable devices. Carries data for device identification, status, and control.
Smoke Sensitivity
The measure of how much smoke is required to trigger an alarm, expressed in obscuration per unit distance. Typical range is 1-4% obscuration per foot.
Sprinkler Supervision
The monitoring of sprinkler system valve positions and water flow. Ensures valves are open and alerts when water flows (indicating sprinkler activation or leak).
Standalone Detector
A self-contained smoke alarm with its own power source (battery or AC with battery backup) and built-in sounder. Not connected to a fire alarm system control panel.
Strobe
A visual notification device that produces flashing light to alert occupants who may not hear audible alarms. Required for ADA compliance and in high-noise environments.
Supervisory Signal
A signal indicating an off-normal condition that requires attention but is not a fire alarm, such as a closed sprinkler valve or low system pressure.
Temporal Pattern
The distinctive three-pulse fire alarm evacuation signal pattern (on-off-on-off-on-off, pause, repeat) required by NFPA 72 and ISO 8201 for immediate evacuation.
Trouble Signal
A signal indicating a fault in the fire alarm system, such as a wiring problem, low battery, or device malfunction. Requires investigation and repair.
UL (Underwriters Laboratories)
An independent testing and certification organization. UL 217 covers smoke alarms, UL 268 covers system smoke detectors. UL listing is required for fire alarm products in the US.
VESDA
Very Early Smoke Detection Apparatus - a brand of aspirating smoke detection system that provides very early warning of fire conditions. Used in data centers, clean rooms, and other critical facilities.
Video Smoke Detection
Technology that uses video cameras and software algorithms to detect smoke or flames in the cameras field of view. Provides visual verification of fire events.
Visible Notification
Notification devices that use light (strobes or LEDs) to alert occupants. Required by ADA for hearing-impaired individuals and in noisy environments.
Water Flow Switch
A device that detects water flow in a sprinkler system pipe and sends an alarm signal to the fire alarm control panel. Indicates sprinkler activation.
Wireless Fire Alarm System
A fire alarm system where detectors and other devices communicate with the control panel using radio frequency instead of wires. Ideal for retrofits and historic buildings.
Zone
A defined area of a building protected by fire detection devices. In conventional systems, each zone is a separate circuit. Zones help identify the general location of an alarm.