Fire Alarm Systems - NEMA Training Manual| Latest
Update 2026.
acknowledge
To confirm that a message or signal has been received, such as by the pressing of a button or the
selection of a software command.
active multiplex system
A multiplexing system in which signaling devices such as transponders are employed to transmit
status signals of each initiating device or initiating device circuit within a prescribed time
interval so that the lack of receipt of such signal may be interpreted as a trouble signal.
alarm
A warning of fire danger.
addressable device
A fire alarm system component with discrete identification that can have its status individually
identified or that is used to individually control other functions.
adverse condition
Any condition occurring in a communications or transmission channel that interferes with the
proper transmission or interpretation, or both, of status change or control command signals at the
supervising station.
air sampling-type detector
,A detector that consists of a piping or tubing distribution network from the detector to the area(
s) to be protected. An aspiration fan in the detector housing draws air from the protected area
back to the detector through air sampling ports, piping, or tubing. At the detector, the air is
analyzed for fire products.
alarm service
The service required following the receipt of an alarm signal.
alarm signal
A signal indicating an emergency requiring immediate action, such as a signal indicative of fire.
alarm system
A combination of compatible initiating devices, control units, and indicating appliances designed
and installed to produce an alarm signal in the event of fire.
alarm verification feature
A feature of automatic fire detection and alarm systems to reduce unwanted alarms wherein
smoke detectors report alarm conditions after a minimum period of time, or confirm alarm
conditions within a given time period after being reset, in order to be accepted as a valid alarm
initiation signal.
alert tone
An attention-getting signal to alert occupants of the pending transmission of a voice message.
analog initiating device (sensor)
, An initiating device that transmits a signal indicating varying degrees of condition as contrasted
with a conventional initiating device, which can only indicate an on/ off condition.
annunciator
A unit containing one or more indicator lamps, alphanumeric displays, or other equivalent means
in which each indication provides status information about a circuit, initiating device, condition,
or location.
approved
Acceptable to the authority having jurisdiction (AHJ).
audible signal
An audible signal is the sound made by one or more audible notification appliances such as bells,
horns, or speakers in response to the operation of an initiating device.
authority having jurisdiction
The organization, office, or individual responsible for approving equipment, materials, an
installation, or a procedure. NFPA 72 contains an annex item commenting on the definition for
"Authority Having Jurisdiction" as follows: A-3.2.2 Authority Having Jurisdiction (AHJ). The
phrase "authority having jurisdiction" is used in NFPA documents in a broad manner, since
jurisdictions and approval agencies vary, as do their responsibilities. Where public safety is
primary, the authority having jurisdiction may be a federal, state, local, or other regional
department or individual such as a fire chief; fire marshal; chief of a fire prevention bureau, labor
department, or health department; building official; electrical inspector; or others having
statutory authority. For insurance purposes, an insurance inspection department, rating bureau, or
Update 2026.
acknowledge
To confirm that a message or signal has been received, such as by the pressing of a button or the
selection of a software command.
active multiplex system
A multiplexing system in which signaling devices such as transponders are employed to transmit
status signals of each initiating device or initiating device circuit within a prescribed time
interval so that the lack of receipt of such signal may be interpreted as a trouble signal.
alarm
A warning of fire danger.
addressable device
A fire alarm system component with discrete identification that can have its status individually
identified or that is used to individually control other functions.
adverse condition
Any condition occurring in a communications or transmission channel that interferes with the
proper transmission or interpretation, or both, of status change or control command signals at the
supervising station.
air sampling-type detector
,A detector that consists of a piping or tubing distribution network from the detector to the area(
s) to be protected. An aspiration fan in the detector housing draws air from the protected area
back to the detector through air sampling ports, piping, or tubing. At the detector, the air is
analyzed for fire products.
alarm service
The service required following the receipt of an alarm signal.
alarm signal
A signal indicating an emergency requiring immediate action, such as a signal indicative of fire.
alarm system
A combination of compatible initiating devices, control units, and indicating appliances designed
and installed to produce an alarm signal in the event of fire.
alarm verification feature
A feature of automatic fire detection and alarm systems to reduce unwanted alarms wherein
smoke detectors report alarm conditions after a minimum period of time, or confirm alarm
conditions within a given time period after being reset, in order to be accepted as a valid alarm
initiation signal.
alert tone
An attention-getting signal to alert occupants of the pending transmission of a voice message.
analog initiating device (sensor)
, An initiating device that transmits a signal indicating varying degrees of condition as contrasted
with a conventional initiating device, which can only indicate an on/ off condition.
annunciator
A unit containing one or more indicator lamps, alphanumeric displays, or other equivalent means
in which each indication provides status information about a circuit, initiating device, condition,
or location.
approved
Acceptable to the authority having jurisdiction (AHJ).
audible signal
An audible signal is the sound made by one or more audible notification appliances such as bells,
horns, or speakers in response to the operation of an initiating device.
authority having jurisdiction
The organization, office, or individual responsible for approving equipment, materials, an
installation, or a procedure. NFPA 72 contains an annex item commenting on the definition for
"Authority Having Jurisdiction" as follows: A-3.2.2 Authority Having Jurisdiction (AHJ). The
phrase "authority having jurisdiction" is used in NFPA documents in a broad manner, since
jurisdictions and approval agencies vary, as do their responsibilities. Where public safety is
primary, the authority having jurisdiction may be a federal, state, local, or other regional
department or individual such as a fire chief; fire marshal; chief of a fire prevention bureau, labor
department, or health department; building official; electrical inspector; or others having
statutory authority. For insurance purposes, an insurance inspection department, rating bureau, or
