AR Fire Alarm cheat sheet

An initiating device circuit (IDC) connects detection devices to the panel; a notification appliance circuit (NAC) powers horns, strobes, and speakers.

Class B circuits are two-wire, unprotected-path styles (Styles B, C, D); a single open stops devices beyond the break from reporting.

Class A circuits (Styles D, E, F) return the path to the panel, so a single open leaves all devices operational.

Two-wire (conventional) detectors draw operating power from the IDC and alarm by dropping circuit impedance; four-wire detectors need separate power and use relay contacts.

NFPA 72 spacing for smooth-ceiling smoke detectors: 30 ft (9.1 m) maximum from any point, 21 ft (6.4 m) between detectors on a square grid with 10 ft ceiling.

Spot-type heat detector spacing is 50 ft (15.2 m) maximum on smooth ceilings; reduce spacing per NFPA 72 Table 17.6.3.5.1 for ceiling height.

Total (100%) smoke detector coverage in a corridor is required when the corridor is used as part of the egress path and the system is installed to that standard.

Elevator recall, door release, and smoke-control functions are suppression or building-system interfaces, not notification functions.

A waterflow switch on a sprinkler riser is an initiating device; a tamper switch monitors valve position and is supervisory, not alarm.

NFPA 72 is the National Fire Alarm and Signaling Code; NFPA 70 (NEC) Article 760 governs fire alarm wiring methods.

NFPA 101 (Life Safety Code) sets occupancy-based detection, notification, and egress requirements that drive system design.

NEC 760.41/760.43: fire alarm power circuits must be mechanically protected and cannot share a raceway with non-power-limited circuits unless separated.

NFPA 72 requires visible notification appliances in public and common areas, and in areas where audible signals may be ineffective or ambient sound exceeds 105 dBA.

Audible signal sound pressure must be at least 15 dBA above ambient, or 5 dBA above ambient if ambient exceeds 105 dBA, measured at 10 ft (3 m).

NFPA 72 inspection, testing, and maintenance frequencies: monthly for batteries under load, quarterly for waterflow devices, annually for most initiating and notification devices.

Record retention: inspection and test records must be kept until the next inspection or test, and at least one year for most systems.

A fire alarm control unit must be listed to UL 864; initiating devices to UL 268/UL 521 and notification appliances to UL 1971/UL 464.

Ohm's law: V = I × R; power: P = V × I = I²R = V²/R.

Voltage drop on a NAC: Vdrop = 2 × I × R × L / 1000 for copper resistance in ohms per 1000 ft, using the round-trip length.

NAC voltage drop limit: appliance voltage must stay within the listed operating range; design to no more than 10% drop from panel terminals.

Battery standby sizing: required amp-hours = (standby current × standby hours) + (alarm current × alarm minutes / 60), then apply a 20% derating factor.

NEC 760.130: fire alarm circuits must be installed in raceway, metal-clad cable, or other approved methods; exposed wiring must be protected from physical damage.

Fire alarm conductors must be color-coded or otherwise identified; red is the customary color for fire alarm cable.

All fire alarm equipment must be grounded per NEC Article 250; the panel's grounding electrode conductor must be sized per Table 250.66.

Supervisory current on a conventional IDC is typically a few milliamps; alarm current is much higher, and the panel distinguishes states by current level.

Arkansas fire protection systems are regulated by the Arkansas Fire Protection Licensing Board under Arkansas Code Title 20, Chapter 22.

The Board licenses fire alarm contractors, fire sprinkler contractors, and fire extinguisher firms, and issues individual licenses for installers and technicians.

A fire alarm contractor license is required to install, alter, repair, or service fire alarm systems in Arkansas; unlicensed work is a violation subject to penalty.

License renewal is required annually; continuing education hours must be completed and documented before renewal.

A licensed contractor must obtain permits and inspections from the local authority having jurisdiction (AHJ) before installation or alteration.

Individual installers and technicians must work under the supervision of a licensed contractor and hold the appropriate individual license or certification.

The Board may suspend or revoke a license for code violations, fraudulent work, or failure to comply with Board rules; it also investigates complaints.

Arkansas adopts NFPA 72 and NFPA 101 by reference through Board rules; the edition adopted is the one referenced in the current Board rules.