AA LISTING: Refers to the method of signal transmission utilized by an ALARM SYSTEM to communicate an emergency signal to a CENTRAL STATION. The category itself is no longer being used but in order for an installation to have received a "AA Listing", the equipment and installation methods also had to meet a very strict standard.
"A" WEIGHTED: When measuring sound pressure levels, this scale on the meter most closely resembles the response of the human ear.
ACOUSTICALLY DISTINGUISHABLE SPACE (ADS): Is a space (or area) within a building that can be distinguished from other spaces (or areas) either acoustically, environmentally or by the usage (type of occupancy), and is used in designing a speaker layout that considers factors such as reverberation time, sound reflective materials (used in the area) and ambient sound pressure levels. An ADS allows the building designer to divide a building into areas (or spaces) and identify those areas that require a higher level of speech intelligibility.
ACTIVE COMMUNICATION: Refers to a method of signal transmission to a qualified central monitoring station in which communication between the premises fire alarm communicator and the station receiver is continuously supervised. Loss of communication will result in a trouble condition at both the communicator and the receiver and will trigger a predetermined response by personnel at the monitoring centre. See also our sample TIP and DIRECT LINE.
ACTIVE FIELD DEVICE: Any of a family of addressable fire alarm components and modules that include heat detectors, smoke detectors, manual stations, monitor modules, relay modules, etc. These devices incorporate circuitry that enable them to communicate bi-directionally with the common control or transponder.
AHU: Air Handling Unit.
ALARM SYSTEM: Consists of a CONTROL PANEL, INPUT DEVICES, OUTPUT DEVICES, and their associated WIRING to comprise a means of notifying the occupants of a building (or communicating to a CENTRAL STATION) of an INTRUSION, FIRE, FLOOD, SUPERVISORY SIGNAL, etc.
ALARM VERIFICATION: A method by which an alarm (or supervisory) event must undergo another process in order to confirm an actual condition exists which requires the activation of an OUTPUT DEVICE. This may include the requirement for another independent device monitoring the same protected area to enter an ALARM state. It may also involve PROGRAMMING SOFTWARE (or FIRMWARE) that requires one event trigger to follow another within a specified (and usually programmable) time frame.
ANNUNCIATOR: A device which displays ALARM, SUPERVISORY, and TROUBLE conditions and that is most often used when the main fire or burglary control unit is mounted in a location not easily accessible. Modern ANNUNCIATORS have the ability to mimic the control functions of the main panel.
APPROVED INDIVIDUAL (or APPROVED AGENCY): An individual (or organization) that has demonstrated the required technical ability and knowledge to perform maintenance, inspection, and repair on specific equipment or systems to the satisfaction of the local authority. Manufacturer specific training may be included in the requirements to achieve "approval". A good example of approval criteria can be found on the City of Vancouver's List of Approved Fire Alarm Verification Agencies.
AUTHORITY HAVING JURISDICTION (AHJ): An individual or organization that adopts and enforces the codes, rules, and by-laws which govern the various concerns of a community. Commonly referred to as the "final authority" for any matters relating to LIFE SAFETY and BUILDING CONSTRUCTION within that specific community