NICET Fire Alarm cheat sheet

NFPA 72 is the National Fire Alarm and Signaling Code covering design, installation, and testing; NEC Article 760 covers fire alarm wiring; UL 864 lists control units.

NFPA 72 documentation requirements include drawings, specifications, a record of completion, and inspection/testing records; the record of completion is completed by the installing contractor and certified by the owner or AHJ representative.

Circuits and pathways are classified as Class A, B, C, D, E, N, or X: Class A continues to operate during a single open or ground fault, Class B does not, and Class X survives open, short, and ground faults.

Equipment must be listed for its purpose: UL 268 smoke detectors, UL 521 heat detectors, UL 464 audible appliances, UL 1971 visible appliances, UL 1481 power supplies.

The building code and NFPA 101 establish when a fire alarm system is required; NFPA 72 establishes how it is designed and installed; the AHJ enforces both and may accept approved alternatives.

As-built drawings must reflect the actual installed configuration, including device locations, addresses, zones, and circuit routing.

Manufacturer published instructions are code-required installation documents; where they conflict with the plans, the more restrictive requirement governs and deviations need AHJ approval.

Shop (submittal) drawings are prepared before installation and show device locations, circuit routing, voltage drop, and battery calculations; they require review and approval before work starts.

Reacceptance testing is required whenever a system component is modified, repaired, added, or replaced, and must include verification of interfaces with other systems.

Smoke detector spacing on a smooth ceiling equals the listed spacing (commonly 30 ft), and no point on the ceiling may be farther than 0.7 times the listed spacing (21 ft for 30 ft spacing) from a detector.

Ceiling-mounted detectors must be at least 4 in from side walls; wall-mounted detectors must have the top of the detector 4 in to 12 in below the ceiling.

Detectors must be kept at least 36 in from HVAC supply diffusers and out of dead-air spaces such as ceiling corners and closets.

Public mode audibility requires 15 dBA above average ambient sound, or 5 dBA above maximum ambient sound lasting 60 seconds or more; sleeping areas require 75 dBA at the pillow.

Wall-mounted visible appliances are installed with the lens 80 in to 96 in above finished floor and at least 6 in below the ceiling; candela rating must satisfy the manufacturer spacing table for the room size.

Manual fire alarm boxes are mounted 42 in to 48 in above finished floor and within 5 ft of the exit door they serve.

A waterflow alarm must annunciate within 90 seconds after flow begins; alarm signals are processed within 10 seconds and trouble signals within 200 seconds.

Addressable device counts are limited by control unit listing and by signaling line circuit current and voltage drop; conventional zone device counts are limited by the control unit listing.

A positive alarm sequence allows 15 seconds to acknowledge a signal and up to 180 seconds of investigation by trained personnel before general alarm.

Class B circuits require an end-of-line device and annunciate an open fault as a trouble; Class A circuits return to the control unit and keep operating during a single open.

Power-limited fire alarm cable must be supported at intervals not exceeding 4.5 ft and within 12 in of boxes unless installed in raceway; FPLR is for risers and FPLP for plenums.

Keep fire alarm power-limited conductors at least 2 in from electric light and power conductors or separated by a barrier, and cross power conductors at right angles.

Two-wire voltage drop: Vd = (2 x K x I x L) / CM, with K = 12.9 ohm-cmil/ft for copper, I in amperes, and L the one-way length in feet.

For multiple notification appliances, add the current-resistance drop of each conductor segment to find the voltage at the last appliance, which must be at or above its listed minimum.

Battery sizing: (standby current x standby hours) + (alarm current x alarm minutes / 60), then multiply the result by 1.20 for battery aging.

Standby requirement for commercial systems is typically 24 hours of standby followed by 5 minutes of alarm operation at the calculated load.

Conventional initiating devices are wired in parallel across the zone conductors; a short circuit is seen as an alarm and an open circuit as a trouble.

All fire alarm circuits must be electrically supervised for opens, shorts, and grounds where required, with ground faults detected and annunciated at the control unit.

Acceptance testing requires operating 100 percent of initiating devices and notification appliances and recording results on the record of completion and test forms.

Smoke detector sensitivity is checked within 1 year of installation and every alternate year thereafter unless the manufacturer requires more frequent checking.

Duct smoke detectors are tested annually using smoke or approved aerosol while verifying airflow and correct sampling tube installation.

Per the NFPA 72 testing table, waterflow switches are tested semiannually and valve supervisory switches quarterly.

Notification appliances are functionally tested annually, including measurement of audibility and verification of visible appliance operation.

Batteries are inspected for charging current and terminal condition, load tested, and replaced when capacity falls below 80 percent of rated capacity.

Any impairment requires a documented procedure: notify the monitoring company and occupants, and provide a fire watch where required by the AHJ.

Test records must be documented, retained, and made available to the AHJ on request; reacceptance testing follows any modification or repair.

Detectors must be tested with smoke, approved aerosol, or the manufacturer's listed method; disabling a device to prevent nuisance alarms is not an acceptable test.