Terminology
Address - A set of numbers that allow the panel to identify each individual device in an addressable system: every number is unique per device.
Alarm - Used to describe the entire system or device in an active state. A general fire alarm will cause an evacuation of a building, but some other types of alarm may not.
Authority Having Jurisdiction (AHJ) - Most of the time this is the fire department that gets to make the decision on certain requirements.
Class A - A wiring method for conventional circuits, SLC loops, NAC circuits, and auxiliary circuits that includes a pair of wires going out from the panel, through all the devices, and returning back to the panel to a separate, redundant set of terminals. The alarm panel supervises this wiring method by checking for continuity throughout the wiring run. Class A wiring is failsafe in the event of a single open fault.
Class B - A wiring method for conventional circuits, SLC loops, NAC circuits, and auxiliary circuits that includes a pair of wires going out from the panel, through all the devices, and terminating at the last device in the line with an end-of-line (EOL) resistor. The alarm panel supervises this wiring method by checking for this specific resistance. An open fault in a Class B wiring circuit will disable all devices downstream from the fault and report a trouble to the alarm panel. The advantage of Class B is that you don't need to run a pair of wires from the last device back to the panel.
DACT (Digital Alarm Communicator Transmitter) - A component of some systems that contacts a monitoring center when the system is in alarm, trouble, or supervisory.
EOL (End Of Line) Resistor - A component of conventional systems that allows the panel to monitor all zones & NACs for proper connection. A break in the wire between the panel & a resistor will cause a trouble condition.
FACP - Fire Alarm Control Panel.
Ground Fault - A condition where the fire alarm control panel is not properly connected to a ground wire.
Initiating Device Circuit (IDC) - Sometimes referred to as a zone, this circuit contains anything that activates the fire alarm system (e.g. manual pull stations, smoke detectors, waterflow switches, etc.). Initiating device circuits are grouped into zones, and any activated device in that initiating device circuit will register as an alarm condition for that zone. Initiating device circuit zones do not report individual device addresses to the panel.
Latching/Non-Latching - Term used to describe two types of smoke detectors: latching detectors "latch" in alarm & need their power cut to be reset, while non-latching detectors reset from an alarm state automatically. Most commercial detectors are the latching type while most residential detectors are the non-latching type.
Local Alarm/Local Fire Alarm - Sometimes referred to as "protected premesis" systems per NFPA 72, a fire alarm condition that either occurs in & evacuates only part of a building or that does not automatically notify the fire department. Many older systems were local alarm only.
NFPA 72 - The National Fire Alarm and Signaling Code. NFPA 72 is a publication published by the National Fire Protection Association, updated every three years, that defines minimum design, installation, inspection, testing, and maintenance criteria for fire alarm, emergency communication, and mass notification systems in the United States.
Non-Power Limited - A circuit that is fused or has a breaker, an example would be the AC power that comes into the panel, or batteries.
Notification Appliance Circuit (NAC) - Term used for circuits containing horns, strobes, and speakers. Usually known as a "Sounder Circuit" on European panels. Security panels commonly call these "Bell Circuits"
Programing -The data stored on a panel which tells it what to do, and how to behave.
Power Limited - A circuit that has a fixed voltage and amperage, which cannot be exceeded. Power Limited circuits are usually NACs and IDCs.
Power Loop - Sometimes known as an "active" loop, is when a circuit is outputting voltage to the highest potential. For example, this is used when a NAC goes into alarm.
Resettable - Refers to devices or circuits that reset to a normal state when the system goes through the resetting process. Resettable Power will temporarily be cut off when the system is reset.
Restorable - Refers to devices that are capable of being reused after they have been activated. Some heat detectors, for example, cannot be restored once tripped.
Signaling Line Circuit (SLC) - Term used for the circuit responsible for all devices on the data circuit for Addressable / Intelligent Systems. This circuit can be both input and output because the signal is digital.
Supervision Loop - Sometimes known as an "inactive" loop, is when a circuit is putting out just enough voltage to ensure there is no open wire or other fault, but not enough voltage to activate a device, such as a notification appliance.
Supervisory - A type of signal that is used for non-fire related situations. Examples may include CO Detection and Sprinkler Valve Tamper Switches.
Trouble/Fault - Used to describe anything wrong with the system, such as an open circuit or a ground fault.