AL Fire Alarm cheat sheet

NFPA 72 defines a fire alarm system as any combination of initiating devices, notification appliances, and control equipment arranged to detect and signal a fire.

Initiating devices are either automatic (smoke, heat, flame, waterflow) or manual (pull stations); notification appliances include horns, strobes, speakers, and combination units.

A conventional zone circuit typically supervises wiring with a DC voltage and uses end-of-line resistors to detect open circuits; alarm condition is a drop in resistance.

Addressable systems use a digital protocol to individually identify devices; each device has a unique address and the panel polls devices for status.

Smoke detectors: ionization is better for flaming fires, photoelectric is better for smoldering fires; both must be listed to UL 268.

Heat detectors: fixed-temperature activates at a set temperature (e.g., 135°F), rate-of-rise activates when temperature increases rapidly (e.g., 15°F per minute).

Notification appliance circuits (NACs) must be supervised for opens, shorts, and grounds; they often use a reverse-polarity supervision scheme.

Alarm signals must be distinct from trouble and supervisory signals; trouble signals indicate a fault in the system, supervisory signals indicate an off-normal condition in a monitored system (e.g., sprinkler valve closed).

In a protected premises system, the alarm signal must be transmitted to a central station or remote supervising station within 90 seconds of activation, unless otherwise permitted.

Alabama adopts the NFPA 72 National Fire Alarm and Signaling Code as the basis for fire alarm installation requirements, often with local amendments.

The Alabama Fire College and Personnel Standards Commission establishes licensing and certification requirements for fire alarm technicians.

The Alabama Electronic Security Board of Licensure (AESBL) regulates alarm system contractors and technicians, including fire alarm, in Alabama.

A statewide fire alarm contractor license is required to install, service, or maintain fire alarm systems; local jurisdictions may require additional permits and inspections.

The Alabama Building Code (based on the International Building Code) and NFPA 101 Life Safety Code govern when a fire alarm system is required based on occupancy and building characteristics.

NFPA 72 requires that all fire alarm systems be inspected, tested, and maintained in accordance with the frequencies specified in Table 14.4.3.2 (e.g., annual for most devices).

In Alabama, fire alarm plans must be submitted to the local authority having jurisdiction (AHJ) for review and approval before installation; the AHJ may be the state fire marshal or local fire department.

The Alabama Fire Marshal's Office enforces fire safety codes in state-owned and certain other buildings; local fire marshals enforce in their jurisdictions.

Ohm's Law: V = I × R, where V is voltage in volts, I is current in amperes, and R is resistance in ohms.

Power formula: P = V × I (DC), or P = I²R; for AC circuits, account for power factor.

Voltage drop in a conductor: VD = (2 × K × I × L) / CM, where K is resistivity (12.9 for copper), I is current, L is one-way length, CM is circular mils.

Fire alarm circuits must be separated from power-limited circuits per NEC Article 760; use CL2, CL3, or FPL-rated cable as required.

Class A circuits provide a redundant path and continue to operate after a single open; Class B circuits do not have redundancy and will be impaired by an open.

Ground faults occur when a conductor unintentionally contacts ground; they can be detected by supervising the circuit for current imbalance.

Wire gauge selection must ensure voltage drop does not exceed the manufacturer's specified limits for notification appliances (often 10% of nominal voltage).

Battery backup calculations: standby current × standby hours + alarm current × alarm hours = ampere-hours required; then apply a derating factor (e.g., 1.2) and aging factor.

Impedance (Z) combines resistance and reactance: Z = √(R² + X²), where X is reactance in ohms.

Alabama requires a state license to engage in the business of installing, servicing, or maintaining alarm systems; working without a license can result in fines and criminal penalties.

License types may include qualifying agent, technician, and apprentice; each has specific experience, training, and examination requirements.

Continuing education (CE) is typically required for license renewal; the number of hours and subject areas are set by the licensing board.

Contractors must carry general liability insurance and workers' compensation as required by state law and licensing rules.

A written contract should specify the scope of work, code compliance, warranty terms, and limitations of liability; avoid guaranteeing that a system will prevent all fire damage.

Obtain permits and schedule inspections with the AHJ before covering wiring or energizing equipment; final acceptance testing is required.

Keep accurate records of installation, testing, and maintenance; NFPA 72 requires documentation to be retained and made available to the AHJ.

Lien laws in Alabama allow contractors to file a mechanic's lien for unpaid work; follow statutory notice requirements to preserve lien rights.

Business practices should include proper handling of hazardous materials, employee safety training, and adherence to OSHA regulations.