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A fire alarm system component with discrete identification that can have its status individually identified or that is used to individually control other functions.
Addressable device
A detector consisting of piping or tubing distribution from the detector unit to the area or areas to be protected. An air pump draws air from the protected area back to the detector through the air sampling ports and piping or tubing. At the detector, the air is analyzed for fire products.
Air sampling detector
A signal indicating an emergency requiring immediate action, such as an alarm for fire from a manual station, water flow device, or automatic fire alarm system.
Alarm signal
The upper surface of a space, regardless of height. Areas with a suspended ceiling would have two ceilings: one visible from the floor, and one above the suspended ceiling.
Ceiling
A control function that attempts to return a system or device to its normal, non-alarm state.
Reset
A signal initiated by the fire alarm system or device that indicates a fault in a monitored circuit or component.
Trouble signal
An automatic sequence that results in an alarm signal, even when manually delayed for investigation, unless the system is reset must not be longer than three minutes (180 seconds) but can be adjustable to allow on-site personnel to check the alarm.
Positive alarm sequence
An act of Congress intended to ensure civil rights for physically challenged people.
Americans with Disabilities Act (ADA):
The height from the continuous floor of a room to the continuous ceiling of a room or space.
Ceiling height
A device used to terminate a supervised circuit. An EOL is normally a resistor or a diode placed at the end of a two-wire circuit to maintain supervision.
End-of-line (EOL) device
A device that detects the infrared, ultraviolet, or visible radiation produced by a fire. Some devices are also capable of detecting the flicker rate (frequency) of the flame.
Flame detector
A device with the control circuits necessary to furnish power to a fire alarm system, receive signals from alarm-initiating devices (and transmit them to audible alarm-indicating appliances and accessory equipment), and electrically supervise the system installation wiring and primary (main) power. The control unit can be contained in one or more cabinets in adjacent or remote locations.
Control unit
A system in which all or some of the circuits are actuated by automatic devices, such as fire detectors, smoke detectors, heat detectors, and flame detectors.
Automatic fire alarm system
This is the update of the NFPA standards book that contains the former NFPA 71, NFPA 72®, and NFPA 74 standards, as well as the NFPA 1221 standard. The NFPA 72® is revised every three years.
National Fire Alarm and Signaling Code
A system component that provides an interface between the transmission channel and signaling line circuits, initiating device circuits, or control units.
Transmitter
The active subassemblies at the supervising station used for signal receiving, processing, display, or recording of status change signals. The failure of one of these subassemblies causes the loss of a number of alarm signals by that unit.
System unit
An audible signal is the sound made by one or more audible indicating appliances, such as bells, chimes, horns, or speakers, in response to the operation of an initiating device.
Audible signal
An open, ground, or short condition on any line(s) extending from a control unit, which could prevent normal operation.
Fault
An audible signal appliance in which energy produces a sound by imparting motion to a flexible component that vibrates at some nominal frequency.
Horn
The action of light being reflected or refracted off particles of combustion, for detection in a modern-day photoelectric smoke detector. This is called the Tyndall effect.
Light scattering
Equipment or materials included in a list published by an organization acceptable to the authority having jurisdiction that is concerned with product evaluation, whose listing states either that the equipment or materials meets appropriate standards or has been tested and found suitable for use in a specified manner.
Listed
Any audible or visible signal employed to indicate a fire, supervisory, or trouble condition. Examples of audible signal appliances are bells, horns, sirens, electronic horns, buzzers, and chimes. A visible indicator consists of an incandescent lamp, strobe lamp, mechanical target or flag, meter deflection, or the equivalent. Also called an indicating device.
Notification appliance (device)
A manually or automatically operated device, the normal intended operation of which results in a fire alarm or supervisory signal indication from the control unit. Examples of alarm signal initiating devices are thermostats, manual boxes (stations), smoke detectors, and water flow devices. Examples of supervisory signal initiating devices are water level indicators, sprinkler system valve-position switches, pressure supervisory switches, and water temperature switches.
Initiating device
A signal indicating the need for action in connection with the supervision of guard tours, the fire suppression systems or equipment, or the maintenance features of related systems.
Supervisory signal
A single-stroke or vibrating audible signal appliance that has a xylophone-type striking bar
Chime
A signal pulsed in a prescribed code for each round of transmission.
Coded signal
A condition in which the resistance between a conductor and ground reaches an unacceptably low level.
Ground fault
A reduction in the atmospheric transparency caused by smoke, usually expressed in percent per foot.
Obscuration
Any conductor, optic fiber, radio carrier, or other means for transmitting fire alarm system information between two or more locations.
Path (pathway):
Detectors employing the photoelectric principle of operation using either the obscuration effect or the light-scattering effect for detecting smoke in its chamber.
Photoelectric smoke detectors
A source of electrical operating power, including the circuits and terminations connecting it to the dependent system components.
Power supply
A defined area within the protected premises. A zone can define an area from which a signal can be received, an area to which a signal can be sent, or an area in which a form of control can be executed.
Zone
In the context of fire alarm control panels, tags that identify various zones and sensors by descriptive names. Units may include dual identifiers, one of which is meaningful to the occupants, while the other is helpful to firefighting personnel.
Labeled
A system component at the protected premises to which initiating devices or groups of devices are connected. The DACT will seize the connected telephone line, dial a preselected number to connect to a digital alarm communicator receiver (DACR), and transmit signals indicating a status change of the initiating device.
Digital alarm communicator transmitter (DACT)
A term usually applied to the simultaneous operation of all the audible alarm signals on a system, to indicate the need for evacuation of a building.
General alarm
A circuit to which automatic or manual signal-initiating devices such as fire alarm manual boxes (pull stations), heat and smoke detectors, and water flow alarm devices are connected.
Initiating device circuit (IDC):
A type of photoelectric light-obscuration smoke detector in which the beam spans the protected area.
Projected beam smoke detector
The physical location protected by a fire alarm system.
Protected premises
A device that responds when the temperature of the air surrounding the device reaches a predetermined level, regardless of the rate of temperature rise.
Rate compensation detector
Devices that respond when the temperature rises at a rate exceeding a predetermined value.
Rate-of-rise detectors
The distance between peaks of a sinusoidal wave. All radiant energy can be described as a wave having a wavelength. Wavelength serves as the unit of measure for distinguishing between different parts of the spectrum. Wavelengths are measured in microns, nanometers, or angstroms
Wavelength
organization, office, or individual responsible for approving equipment, installations, or procedures in a particular locality.
Authority having jurisdiction (AHJ)
A term used in electronics to cover all types of unwanted electrical signals.
Noise
A signal from any indicating appliance that is continuously energized.
Non-coded signal
A device in which the detecting element is concentrated at a particular location. Typical examples are bimetallic detectors, fusible alloy detectors, certain pneumatic rate-of-rise detectors, certain smoke detectors, and thermoelectric detectors.
Spot-type detector
In fire systems, a warning of fire danger.
Alarm
The conductors or radio channel as well as the associated equipment used to perform a definite function in connection with an alarm system.
Circuit
Repair service, including periodic inspections and tests, required to keep the protective signaling system and its component parts in an operative condition at all times. This is used in conjunction with replacement of the system and its components when they become undependable or inoperative for any reason
Maintenance
Administers the development and publishing of codes, standards, and other materials concerning all phases of fire and life safety.
National Fire Protection Association (NFPA)
Four widely adopted NFPA codes are
•National Electrical Code® (NFPA 70®)
•National Fire Alarm and Signaling Code® (NFPA 72®)
•Life Safety Code® (NFPA 101®)
•Fire Code (NFPA 1)
Acceptable to the authority having jurisdiction (AHJ).
Approved
An assembly of communications facilities and central office equipment, operated jointly by authorized common carriers, that provides the general public with the ability to establish communications channels via discrete dialing codes.
Public switched telephone network (PSTN):
A system installed in accordance with the applicable code to transmit alarm, supervisory, and trouble signals from one or more protected premises to a remote location where appropriate action is taken
Remote supervising station fire alarm system
The phenomenon in which the upward movement of smoke and gases ceases due to a loss of buoyancy.
Stratification
A device that detects abnormally high temperature or abnormally high rate of temperature rise.
Heat detector
A status indication communicated by electrical or other means.
Signal
A circuit or path between any combination of circuit interfaces, control units, or transmitters over which multiple system input signals or output signals (or both input signals and output signals) are carried
Signaling line circuit (SLC)
A device that detects visible or invisible particles of combustion.
Smoke detector
A horizontally measured dimension related to the allowable coverage of fire detectors.
Spacing
A feature of a fire control unit that allows for a delay in the activation of alarms upon receiving an initiating signal from one of its circuits. If approved by the authority having jurisdiction (AHJ), the supervising station has up to 90 seconds to verify that the signal is an unwanted alarm commonly used in hotels, motels, hospitals, and institutions with large numbers of smoke detectors.
Alarm verification
Telephone company service that provides reduced costs for certain telephone call arrangements. In-WATS or 800-number service calls can be placed from anywhere in the continental United States to the called party at no cost to the calling party. Out-WATS is a service whereby, for a flat-rate charge, dependent on the total duration of all such calls, a subscriber can make an unlimited number of calls within a prescribed area from a particular telephone terminal without the registration of individual call charges.
Wide area telephone service (WATS)
A systematic program using randomly selected follow-up inspections of the certified system installed under the program, which allows the listing organization to verify that a fire alarm system complies with all the requirements of the NFPA 72® code.
Certification
A notification appliance that alerts by the sense of sight.
Visible notification appliance