ID Fire Alarm flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

NFPA 72

The National Fire Alarm and Signaling Code, which governs installation, inspection, testing, and maintenance of fire detection and alarm systems, including pathway classes and detector spacing rules.

Class A pathway

A supervised circuit that continues to operate when a single open occurs, because the wiring is routed out and back to the panel; it does not inherently survive a short circuit.

Class B pathway

A supervised circuit with an end-of-line resistor and no redundant path; a single open prevents devices beyond the break from communicating with the control panel.

Class X pathway

A pathway that survives both a single open and a single short circuit, achieved with redundant wiring and isolation; used where high survivability is required.

Style B initiating circuit

A conventional initiating device circuit using an end-of-line resistor with no redundancy; a single open prevents alarms from devices beyond the break from reaching the panel.

Temporal-3 pattern

The standard audible evacuation signal: three pulses, a pause, then repeat; it is distinct from the temporal-4 pattern used for carbon monoxide alarms.

Addressable system

A system using a signaling line circuit where each device has a unique address, so the panel annunciates the specific device rather than only a zone.

Supervisory signal

A signal indicating an off-normal condition of a system component, such as a closed sprinkler control valve or low air pressure, rather than an actual fire alarm.

Trouble signal

A signal indicating a fault in the system itself, such as an open circuit, ground fault, or battery failure, which may impair the system's ability to detect or notify.

Signal priority

Alarm signals take precedence over supervisory and trouble signals; the control unit must display the highest-priority condition and must not let lower-priority signals mask an alarm.

Smoke detector spacing

On smooth ceilings, spot-type smoke detectors are spaced 30 ft (9.1 m) apart, with the first detector within 15 ft (4.6 m) of any wall and 900 sq ft (84 sq m) maximum coverage.

Manual pull station height

Manual fire alarm boxes must be mounted 42 to 48 in (1.07 to 1.22 m) above the floor, within 5 ft (1.5 m) of the exit door on the latch side.

Duct smoke detector threshold

Duct smoke detectors are required where air-handling systems exceed 2,000 cfm (0.94 cu m/s), to shut down the unit and limit smoke spread; they do not replace area detection.

Rate-of-rise heat detector

A heat detector that responds to a rapid temperature increase, typically about 15 degrees Fahrenheit per minute, rather than to a fixed absolute temperature threshold.

Waterflow switch

An initiating device on the sprinkler system that detects water flow and must annunciate a waterflow alarm at the panel within 90 seconds of flow.

Valve tamper switch

A supervisory device that monitors the open position of a sprinkler control valve and sends a supervisory signal if the valve is not fully open.

Audible sound level

Notification must produce at least 15 dBA above ambient or 5 dBA above the maximum sound lasting 60 seconds, whichever is greater, measured 10 ft (3 m) from the appliance.

Sleeping area sound level

In sleeping areas, the alarm sound must reach at least 75 dBA at the pillow level, using the temporal-3 evacuation pattern.

Visible appliance mounting

Visible notification appliances are mounted 80 to 96 in (2.03 to 2.44 m) above the floor, and candela rating is selected by room size and mounting height.

Voice intelligibility

Voice evacuation messages must be intelligible, with a minimum acceptable value of 0.50 on the Speech Transmission Index or 0.70 on the Common Intelligibility Scale.

NAC voltage drop

The voltage lost along a notification appliance circuit; it must be calculated so the last appliance still receives its rated voltage, or larger conductors are needed.

Secondary power supply

The battery backup must operate the system for 24 hours of standby plus 5 minutes of alarm, and the battery is sized with a 20 percent derating factor for aging.

Ground fault detection

The control panel must detect and annunciate ground faults on supervised circuits, including the signaling line circuit, notification circuits, and power circuits.

Signaling line circuit

The addressable loop that carries both power and data to devices and must be supervised for opens, shorts, and ground faults so the panel can reach every device.

Silence switch behavior

The silence function silences notification appliances but not alarm processing; a subsequent alarm on the system must resound the notification appliances.

Acceptance testing

Testing performed per NFPA 72 Chapter 14 before the system is accepted, verifying that every initiating device, notification appliance, and control function operates and annunciates correctly.

Battery load test

A test that applies a load to verify battery capacity; the battery is tested annually and replaced when it fails the load test or reaches its recommended service life.

Testing intervals

Monthly inspection of batteries and panel indicators, semiannual testing of duct detectors and waterflow switches, and annual testing of initiating devices, notification appliances, and control functions.

Dirty detector false alarms

Accumulated dust and debris in a smoke detector chamber cause false alarms; detectors must be cleaned per manufacturer instructions or replaced if cleaning is ineffective.

Locating a ground fault

Ground faults are located by isolating circuits section by section, using a clamp-on ammeter or ground fault locator to identify the affected circuit, then repairing the fault.

Record of completion

NFPA 72 Form 72-1 documents that the system was installed per approved plans and tested per Chapter 14, signed by the contractor and the AHJ representative.

As-built drawings

Drawings reflecting the actual installed system, including device locations, addresses, circuit routing, and panel configuration, updated whenever the system is modified.