AK Fire Alarm cheat sheet

A fire alarm system comprises initiating devices, notification appliances, control equipment, and interconnecting wiring supervised against fault conditions.

Addressable systems assign each device a unique digital address; conventional systems use zone circuits where multiple devices share one indicating circuit.

Detector spacing follows NFPA 72 Chapter 17 tables; spacing is generally 30 ft for standard smoke detectors on smooth ceilings up to 10 ft high.

A zone is a defined area of coverage; an annunciator displays status by zone or point and may be remote from the main control unit.

Supervising station types: central station, proprietary, remote supervising, and auxiliary - each with distinct signal routing and staffing rules.

Alarm, trouble, and supervisory signals are distinct conditions; supervisory signals indicate off-normal status of systems like sprinkler valves, not fire.

Spot-type detectors cover a defined area; projected-beam and air-sampling detectors protect large or high-ceiling spaces.

Positive alarm sequence delays notification up to 15 seconds for alarm verification and 180 seconds total for investigation, per NFPA 72.

NFPA 72 governs installation, inspection, testing, and maintenance of fire alarm systems; NFPA 70 (NEC) governs wiring methods and power.

NFPA 101 (Life Safety Code) sets occupancy-based requirements for detection, notification, and means of egress protection.

Alaska Fire Code adopts NFPA 1 and NFPA 101 with state amendments; local jurisdictions may add stricter requirements.

NEC Article 760 covers fire alarm wiring: Class 2/3 circuits use PLTC or FPL cable; NPLFA and PLFA power-limited classifications govern conductor sizing.

Class A circuits survive a single open; Class B circuits do not - survivability requirements depend on occupancy and system type.

NFPA 72 requires smoke detector spacing per the manufacturer's published listing and the coverage tables in Chapter 17.

Inspection, testing, and maintenance frequencies come from NFPA 72 Table 14.4.3.2; smoke detectors are tested annually at minimum.

Record of completion and record of inspection/testing forms (NFPA 72 Figure 7.8.2) document system acceptance and ongoing compliance.

Ionization detectors respond to products of combustion; photoelectric detectors respond to visible smoke - each suits different fire signatures.

Heat detectors are rate-of-rise, fixed-temperature, or combination; they respond slower than smoke detectors and suit spaces with nuisance smoke.

Manual pull stations mount 42–48 in. above finished floor to the operating handle, within 5 ft of an exit door.

Duct smoke detectors sample airflow and are required where air-handling systems exceed 2,000 cfm and serve more than one floor or 15,000 cfm total.

Projected-beam detectors suit large open areas; spacing and beam path must avoid obstructions and be within listed limits.

Air-sampling (ASD) detectors draw air through a pipe network; hole spacing and transport time are set by the manufacturer's listing.

Detector placement must maintain at least 3 ft horizontal distance from air supply diffusers and 36 in. from obstructions per NFPA 72.

Waterflow switches and valve tamper switches are initiating devices; tamper switches typically report supervisory, waterflow reports alarm.

Public mode audibility requires 15 dBA above ambient or 5 dBA above maximum ambient, whichever is greater, measured at 10 ft.

Private mode requires 10 dBA above ambient; sleeping areas require 75 dBA at the pillow or 15 dBA above ambient, whichever is greater.

Visible appliances must meet candela ratings per NFPA 72 Chapter 18; 15 cd minimum for most spaces, higher for larger rooms or sleeping areas.

Strobe mounting height: 80–96 in. above finished floor, or 6 in. below the ceiling, whichever is lower.

Audiovisual synchronization is required where multiple visible appliances are in the same view; synchronization within 10 ms per NFPA 72.

Voice evacuation systems must produce intelligible voice messages; intelligibility is measured by STI or CIS and must meet design criteria.

Notification appliance circuit voltage drop must be calculated to ensure the last appliance receives its listed minimum operating voltage.

Temporal-three pattern is the standard evacuation signal: three pulses, pause, three pulses, pause, three pulses, long pause.

Primary power: 120 VAC dedicated branch circuit; secondary power: batteries or generator sized for 24 hours standby plus 5 minutes alarm (or 15 min voice).

Battery capacity calculation: (standby current × standby hours) + (alarm current × alarm minutes/60) = ampere-hours required, then apply a 1.2 derating factor.

Class A circuits require a return path; a single open does not disable the circuit. Class B circuits lose function beyond an open.

Supervised circuits detect opens, shorts, and ground faults; end-of-line resistors terminate Class B circuits and must be at the last device.

NAC voltage drop: Vdrop = 2 × I × R × length, where R is resistance per unit length; keep last-device voltage above listed minimum.

Power-limited circuits must be separated from non-power-limited circuits by 2 in. or a barrier per NEC 760.

Ground fault detection is required on the system; a single ground fault should not cause an alarm or trouble that disables protection.

Battery recharge: the charging system must restore batteries to 80% capacity within 24 hours per NFPA 72.

The fire alarm control unit (FACU) processes initiating signals, activates notification, and reports alarm, trouble, and supervisory conditions.

Alarm signal processing: the control unit must activate notification within 10 seconds of an alarm signal from an initiating device.

Trouble signals must annunciate within 200 seconds of a fault; distinct audible and visual trouble indication is required at the FACU.

Supervisory signals (valve tamper, low air, low water) must annunciate within 200 seconds and are distinct from trouble and alarm.

Remote annunciators display zone or point status and must be supervised against connection faults.

Digital alarm communicator transmitters (DACT) transmit via two phone lines or network paths; two distinct transmission paths are required.

Alarm silence and system reset functions must be distinct; silencing notification must not prevent subsequent alarms from reactivating.

Drill switch or key-operated functions allow testing without transmitting signals to the supervising station, when permitted.

NFPA 72 Table 14.4.3.2 sets frequencies: control units annually, initiating devices annually, notification appliances annually (semi-annually in some cases).

Smoke detectors: functional test annually; sensitivity test within one year of installation and every two years thereafter, per manufacturer.

Battery tests: annual load test and 30-minute discharge test; replacement when capacity falls below 80% of rating.

Inspection is visual (no operation); testing verifies functional performance; maintenance restores or replaces components.

Test records must be retained and made available to the authority having jurisdiction; NFPA 72 requires documentation of all tests.

Sprinkler system supervisory devices (valve tamper, waterflow) are tested quarterly or as required by NFPA 25 and NFPA 72.

Voice evacuation systems require intelligibility testing and annual functional testing of the voice message and amplification.

Remote supervising station connections are tested annually; DACT connections tested monthly when required by the AHJ.

Plan review checks: device layout and spacing, circuit classifications, battery calculations, voltage drop, and sequence of operations.

Shop drawings must show device locations, wiring riser diagram, conduit routing, and point-to-point connections.

The record of completion documents system description, device inventory, and certifications signed by the installer and AHJ.

As-built drawings reflect actual installed conditions and must be updated after any modification to the system.

Penetrations through fire-rated assemblies must be firestopped with listed materials to maintain the assembly rating.

Conductor identification: fire alarm circuits must be color-coded or tagged; red is conventional for fire alarm notification.

Sequence of operations matrix defines cause-and-effect for each initiating zone: which outputs activate, delay, or shut down.

Acceptance testing follows NFPA 72 Chapter 14 and requires AHJ witness; deficiencies must be corrected and retested before sign-off.

Mounting heights: manual stations 42–48 in. to handle; visible appliances 80–96 in. to bottom or 6 in. below ceiling.

Smoke detector placement: at least 36 in. from air diffusers and obstructions; 4 in. minimum from wall when wall-mounted.

Conduit fill and support per NEC Chapter 3; fire alarm cable in plenums must be plenum-rated (FPLP).

Separation of power-limited and non-power-limited conductors: 2 in. minimum or listed barrier per NEC 760.30.

Battery calculations and voltage drop calculations must be submitted with plans for AHJ review.

Riser diagrams show panel locations, circuit numbers, and device counts per circuit; point-to-point wiring shows terminal connections.

Documentation package: shop drawings, calculations, sequence of operations, record of completion, and test records.

Modifications to an existing system require updated as-builts and may require a new record of completion and AHJ acceptance test.

A fire alarm system comprises initiating devices, notification appliances, control equipment, and interconnecting wiring supervised against fault conditions.

Addressable systems assign each device a unique digital address; conventional systems use zone circuits where multiple devices share one indicating circuit.

Detector spacing follows NFPA 72 Chapter 17 tables; spacing is generally 30 ft for standard smoke detectors on smooth ceilings up to 10 ft high.

A zone is a defined area of coverage; an annunciator displays status by zone or point and may be remote from the main control unit.

Supervising station types: central station, proprietary, remote supervising, and auxiliary - each with distinct signal routing and staffing rules.

Alarm, trouble, and supervisory signals are distinct conditions; supervisory signals indicate off-normal status of systems like sprinkler valves, not fire.

Spot-type detectors cover a defined area; projected-beam and air-sampling detectors protect large or high-ceiling spaces.

Positive alarm sequence delays notification up to 15 seconds for alarm verification and 180 seconds total for investigation, per NFPA 72.

NFPA 72 governs installation, inspection, testing, and maintenance of fire alarm systems; NFPA 70 (NEC) governs wiring methods and power.

NFPA 101 (Life Safety Code) sets occupancy-based requirements for detection, notification, and means of egress protection.

Alaska Fire Code adopts NFPA 1 and NFPA 101 with state amendments; local jurisdictions may add stricter requirements.

NEC Article 760 covers fire alarm wiring: Class 2/3 circuits use PLTC or FPL cable; NPLFA and PLFA power-limited classifications govern conductor sizing.

Class A circuits survive a single open; Class B circuits do not - survivability requirements depend on occupancy and system type.

NFPA 72 requires smoke detector spacing per the manufacturer's published listing and the coverage tables in Chapter 17.

Inspection, testing, and maintenance frequencies come from NFPA 72 Table 14.4.3.2; smoke detectors are tested annually at minimum.

Record of completion and record of inspection/testing forms (NFPA 72 Figure 7.8.2) document system acceptance and ongoing compliance.

Ionization detectors respond to products of combustion; photoelectric detectors respond to visible smoke - each suits different fire signatures.

Heat detectors are rate-of-rise, fixed-temperature, or combination; they respond slower than smoke detectors and suit spaces with nuisance smoke.

Manual pull stations mount 42–48 in. above finished floor to the operating handle, within 5 ft of an exit door.

Duct smoke detectors sample airflow and are required where air-handling systems exceed 2,000 cfm and serve more than one floor or 15,000 cfm total.

Projected-beam detectors suit large open areas; spacing and beam path must avoid obstructions and be within listed limits.

Air-sampling (ASD) detectors draw air through a pipe network; hole spacing and transport time are set by the manufacturer's listing.

Detector placement must maintain at least 3 ft horizontal distance from air supply diffusers and 36 in. from obstructions per NFPA 72.

Waterflow switches and valve tamper switches are initiating devices; tamper switches typically report supervisory, waterflow reports alarm.

Public mode audibility requires 15 dBA above ambient or 5 dBA above maximum ambient, whichever is greater, measured at 10 ft.

Private mode requires 10 dBA above ambient; sleeping areas require 75 dBA at the pillow or 15 dBA above ambient, whichever is greater.

Visible appliances must meet candela ratings per NFPA 72 Chapter 18; 15 cd minimum for most spaces, higher for larger rooms or sleeping areas.

Strobe mounting height: 80–96 in. above finished floor, or 6 in. below the ceiling, whichever is lower.

Audiovisual synchronization is required where multiple visible appliances are in the same view; synchronization within 10 ms per NFPA 72.

Voice evacuation systems must produce intelligible voice messages; intelligibility is measured by STI or CIS and must meet design criteria.

Notification appliance circuit voltage drop must be calculated to ensure the last appliance receives its listed minimum operating voltage.

Temporal-three pattern is the standard evacuation signal: three pulses, pause, three pulses, pause, three pulses, long pause.

Primary power: 120 VAC dedicated branch circuit; secondary power: batteries or generator sized for 24 hours standby plus 5 minutes alarm (or 15 min voice).

Battery capacity calculation: (standby current × standby hours) + (alarm current × alarm minutes/60) = ampere-hours required, then apply a 1.2 derating factor.

Class A circuits require a return path; a single open does not disable the circuit. Class B circuits lose function beyond an open.

Supervised circuits detect opens, shorts, and ground faults; end-of-line resistors terminate Class B circuits and must be at the last device.

NAC voltage drop: Vdrop = 2 × I × R × length, where R is resistance per unit length; keep last-device voltage above listed minimum.

Power-limited circuits must be separated from non-power-limited circuits by 2 in. or a barrier per NEC 760.

Ground fault detection is required on the system; a single ground fault should not cause an alarm or trouble that disables protection.

Battery recharge: the charging system must restore batteries to 80% capacity within 24 hours per NFPA 72.

The fire alarm control unit (FACU) processes initiating signals, activates notification, and reports alarm, trouble, and supervisory conditions.

Alarm signal processing: the control unit must activate notification within 10 seconds of an alarm signal from an initiating device.

Trouble signals must annunciate within 200 seconds of a fault; distinct audible and visual trouble indication is required at the FACU.

Supervisory signals (valve tamper, low air, low water) must annunciate within 200 seconds and are distinct from trouble and alarm.

Remote annunciators display zone or point status and must be supervised against connection faults.

Digital alarm communicator transmitters (DACT) transmit via two phone lines or network paths; two distinct transmission paths are required.

Alarm silence and system reset functions must be distinct; silencing notification must not prevent subsequent alarms from reactivating.

Drill switch or key-operated functions allow testing without transmitting signals to the supervising station, when permitted.

NFPA 72 Table 14.4.3.2 sets frequencies: control units annually, initiating devices annually, notification appliances annually (semi-annually in some cases).

Smoke detectors: functional test annually; sensitivity test within one year of installation and every two years thereafter, per manufacturer.

Battery tests: annual load test and 30-minute discharge test; replacement when capacity falls below 80% of rating.

Inspection is visual (no operation); testing verifies functional performance; maintenance restores or replaces components.

Test records must be retained and made available to the authority having jurisdiction; NFPA 72 requires documentation of all tests.

Sprinkler system supervisory devices (valve tamper, waterflow) are tested quarterly or as required by NFPA 25 and NFPA 72.

Voice evacuation systems require intelligibility testing and annual functional testing of the voice message and amplification.

Remote supervising station connections are tested annually; DACT connections tested monthly when required by the AHJ.

Plan review checks: device layout and spacing, circuit classifications, battery calculations, voltage drop, and sequence of operations.

Shop drawings must show device locations, wiring riser diagram, conduit routing, and point-to-point connections.

The record of completion documents system description, device inventory, and certifications signed by the installer and AHJ.

As-built drawings reflect actual installed conditions and must be updated after any modification to the system.

Penetrations through fire-rated assemblies must be firestopped with listed materials to maintain the assembly rating.

Conductor identification: fire alarm circuits must be color-coded or tagged; red is conventional for fire alarm notification.

Sequence of operations matrix defines cause-and-effect for each initiating zone: which outputs activate, delay, or shut down.

Acceptance testing follows NFPA 72 Chapter 14 and requires AHJ witness; deficiencies must be corrected and retested before sign-off.

Mounting heights: manual stations 42–48 in. to handle; visible appliances 80–96 in. to bottom or 6 in. below ceiling.

Smoke detector placement: at least 36 in. from air diffusers and obstructions; 4 in. minimum from wall when wall-mounted.

Conduit fill and support per NEC Chapter 3; fire alarm cable in plenums must be plenum-rated (FPLP).

Separation of power-limited and non-power-limited conductors: 2 in. minimum or listed barrier per NEC 760.30.

Battery calculations and voltage drop calculations must be submitted with plans for AHJ review.

Riser diagrams show panel locations, circuit numbers, and device counts per circuit; point-to-point wiring shows terminal connections.

Documentation package: shop drawings, calculations, sequence of operations, record of completion, and test records.

Modifications to an existing system require updated as-builts and may require a new record of completion and AHJ acceptance test.