GA Fire Alarm cheat sheet

NFPA 72 signal hierarchy: alarm signals take priority over supervisory signals, which take priority over trouble signals; a trouble condition must never suppress or delay an alarm signal.

Initiating device circuits are either Class A (Style D/B) or Class B (Style B/A); Class A survives a single open or ground fault and keeps all devices operational, Class B loses devices beyond the break.

Notification appliance circuit voltage drop: Vdrop = 2 x L x I x R per conductor loop, where R is ohms per foot of the conductor; keep end-of-line voltage at least 85 percent of appliance nameplate rating.

Smoke detector spacing on a smooth ceiling is 30 ft (900 sq ft per detector) with the first detector within 15 ft of any wall; use 0.7 x spacing for beam pockets deeper than 10 percent of ceiling height.

Duct smoke detectors are required where air handling units exceed 2,000 cfm; the detector must be installed in the supply side downstream of filters and ahead of any branch connections.

Spot-type heat detectors: 15 ft spacing for the 135-174 F range and 30 ft for the 575 F range; the listing spacing is halved when the ceiling slope exceeds 1 in 4.

Alarm verification (NFPA 72 Table 17.7.4.2.1.1) delays alarm for 60 seconds max, resets on 10-60 second interruption, and is prohibited on circuits with waterflow switches or manual pull stations.

Supervising station types: central station (listed, two independent paths, retransmission to fire department), proprietary, remote, and protected premises; only central station requires two independent means of signal transmission.

Battery sizing: standby capacity = (alarm current x alarm time) + (standby current x 24 hours) with a 20 percent derating for aging; use 24-hour standby with 5 minutes alarm for commercial occupancies.

Wet pipe sprinkler systems are permitted only in spaces maintained above 40 F; dry pipe systems use a 20-40 psi air charge and the dry pipe valve must trip before water reaches the most remote head.

Light hazard density is 0.10 gpm/sq ft over 1,500 sq ft; ordinary hazard Group 1 is 0.15 over 1,500 sq ft; ordinary hazard Group 2 is 0.20 over 1,500 sq ft (NFPA 13 design curves).

Sprinkler head spacing: 15 ft maximum for light hazard with 225 sq ft per head, 15 ft for ordinary hazard with 130 sq ft per head, and 12 ft for extra hazard with 100 sq ft per head.

Fire pumps require a listed pump, a relief valve for centrifugal pumps, a bypass, and a controller; the pump must deliver 150 percent of rated flow at not less than 65 percent of rated head.

Standpipe classes: Class I (2.5 in. outlets for fire department), Class II (1.5 in. hose stations for occupants), Class III (both); combined systems must be designed for the most demanding demand.

Fire resistance ratings: 2-hour separation for occupancy separations between hazard groups, 1-hour for corridors in most commercial occupancies, and 2-hour for stair enclosures in buildings over 4 stories.

Smoke control: stair pressurization must maintain 0.05 to 0.10 in. w.c. differential; the maximum door opening force at the handle is 30 lbf, and 15 lbf for accessible doors.

Clean agent systems (NFPA 2001) require a discharge within 10 seconds for halocarbon agents and 60 seconds for inert gases; the hold time is 10 minutes at the design concentration.

Flammable liquid storage rooms: NFPA 30 limits Class I liquids to 60 gallons per cabinet and 120 gallons per storage room; cabinets must be listed and labeled with a self-closing door.

Combustible dust hazards (NFPA 652) require a Dust Hazard Analysis (DHA) for any process handling combustible particulate solids; deflagration venting, isolation, and suppression are the three protection strategies.

Commercial cooking: hood suppression systems must be listed to UL 300, protect all cooking surfaces, and shut down the fuel and exhaust fan on activation; the manual pull is 42-48 in. above finished floor.

Paint spray booths require the supply air to be filtered and the exhaust to be interlocked; overspray filters must be replaced when the pressure differential exceeds 0.5 in. w.c.

LP-Gas (NFPA 58): containers over 2,000 gallons require a fixed water spray system; the minimum separation from a building is 25 ft for a 500-gallon tank and 50 ft for tanks over 2,000 gallons.

Hazardous material classification: Class I liquids have a flash point below 100 F; Class II is 100-140 F; Class IIIA is 140-200 F; Class IIIB is at or above 200 F.

Explosion protection: a deflagration vent must be sized per NFPA 68 using the vessel volume, Kst value, and Pmax; the vent area is proportional to the vessel volume to the 2/3 power.

Oxidizing agents and organic peroxides (NFPA 400) require separation from incompatible materials and a maximum storage quantity per control area; a fire alarm must monitor the room.

The Georgia Fire Sprinkler and Fire Alarm licensing program is administered under Georgia law; a fire alarm contractor must hold a state license and employ a certified technician for installation and inspections.

NFPA 72 inspection, testing, and maintenance intervals: weekly for wet pipe alarm devices, monthly for supervisory signal devices, quarterly for waterflow devices, and annually for all initiating devices.

The 2018 (or later) editions of NFPA 1, NFPA 72, and NFPA 101 are adopted by reference through the Georgia Fire Code; local amendments may be stricter than the state code.

Permits are required before installing or altering a fire alarm system; the AHJ must inspect and approve the installation before the system is placed in service.

Records of inspection and testing must be maintained and made available to the AHJ; the records must include the date, the tester, the device tested, and the result.

Plan review submittals must include a battery calculation, a voltage drop calculation, the device layout, and the sequence of operations; the AHJ may reject incomplete submittals.

Only listed and labeled equipment may be installed; the listing mark, the manufacturer, the model, and the compatibility listing must be verified for all initiating and notification devices.

The AHJ has the authority to require additional protection beyond the code minimum when the occupancy poses an unusual hazard; the AHJ decision is final and appealable per local ordinance.

NFPA 72 signal hierarchy: alarm signals take priority over supervisory signals, which take priority over trouble signals; a trouble condition must never suppress or delay an alarm signal.

Initiating device circuits are either Class A (Style D/B) or Class B (Style B/A); Class A survives a single open or ground fault and keeps all devices operational, Class B loses devices beyond the break.

Notification appliance circuit voltage drop: Vdrop = 2 x L x I x R per conductor loop, where R is ohms per foot of the conductor; keep end-of-line voltage at least 85 percent of appliance nameplate rating.

Smoke detector spacing on a smooth ceiling is 30 ft (900 sq ft per detector) with the first detector within 15 ft of any wall; use 0.7 x spacing for beam pockets deeper than 10 percent of ceiling height.

Duct smoke detectors are required where air handling units exceed 2,000 cfm; the detector must be installed in the supply side downstream of filters and ahead of any branch connections.

Spot-type heat detectors: 15 ft spacing for the 135-174 F range and 30 ft for the 575 F range; the listing spacing is halved when the ceiling slope exceeds 1 in 4.

Alarm verification (NFPA 72 Table 17.7.4.2.1.1) delays alarm for 60 seconds max, resets on 10-60 second interruption, and is prohibited on circuits with waterflow switches or manual pull stations.

Supervising station types: central station (listed, two independent paths, retransmission to fire department), proprietary, remote, and protected premises; only central station requires two independent means of signal transmission.

Battery sizing: standby capacity = (alarm current x alarm time) + (standby current x 24 hours) with a 20 percent derating for aging; use 24-hour standby with 5 minutes alarm for commercial occupancies.

Wet pipe sprinkler systems are permitted only in spaces maintained above 40 F; dry pipe systems use a 20-40 psi air charge and the dry pipe valve must trip before water reaches the most remote head.

Light hazard density is 0.10 gpm/sq ft over 1,500 sq ft; ordinary hazard Group 1 is 0.15 over 1,500 sq ft; ordinary hazard Group 2 is 0.20 over 1,500 sq ft (NFPA 13 design curves).

Sprinkler head spacing: 15 ft maximum for light hazard with 225 sq ft per head, 15 ft for ordinary hazard with 130 sq ft per head, and 12 ft for extra hazard with 100 sq ft per head.

Fire pumps require a listed pump, a relief valve for centrifugal pumps, a bypass, and a controller; the pump must deliver 150 percent of rated flow at not less than 65 percent of rated head.

Standpipe classes: Class I (2.5 in. outlets for fire department), Class II (1.5 in. hose stations for occupants), Class III (both); combined systems must be designed for the most demanding demand.

Fire resistance ratings: 2-hour separation for occupancy separations between hazard groups, 1-hour for corridors in most commercial occupancies, and 2-hour for stair enclosures in buildings over 4 stories.

Smoke control: stair pressurization must maintain 0.05 to 0.10 in. w.c. differential; the maximum door opening force at the handle is 30 lbf, and 15 lbf for accessible doors.

Clean agent systems (NFPA 2001) require a discharge within 10 seconds for halocarbon agents and 60 seconds for inert gases; the hold time is 10 minutes at the design concentration.

Flammable liquid storage rooms: NFPA 30 limits Class I liquids to 60 gallons per cabinet and 120 gallons per storage room; cabinets must be listed and labeled with a self-closing door.

Combustible dust hazards (NFPA 652) require a Dust Hazard Analysis (DHA) for any process handling combustible particulate solids; deflagration venting, isolation, and suppression are the three protection strategies.

Commercial cooking: hood suppression systems must be listed to UL 300, protect all cooking surfaces, and shut down the fuel and exhaust fan on activation; the manual pull is 42-48 in. above finished floor.

Paint spray booths require the supply air to be filtered and the exhaust to be interlocked; overspray filters must be replaced when the pressure differential exceeds 0.5 in. w.c.

LP-Gas (NFPA 58): containers over 2,000 gallons require a fixed water spray system; the minimum separation from a building is 25 ft for a 500-gallon tank and 50 ft for tanks over 2,000 gallons.

Hazardous material classification: Class I liquids have a flash point below 100 F; Class II is 100-140 F; Class IIIA is 140-200 F; Class IIIB is at or above 200 F.

Explosion protection: a deflagration vent must be sized per NFPA 68 using the vessel volume, Kst value, and Pmax; the vent area is proportional to the vessel volume to the 2/3 power.

Oxidizing agents and organic peroxides (NFPA 400) require separation from incompatible materials and a maximum storage quantity per control area; a fire alarm must monitor the room.

The Georgia Fire Sprinkler and Fire Alarm licensing program is administered under Georgia law; a fire alarm contractor must hold a state license and employ a certified technician for installation and inspections.

NFPA 72 inspection, testing, and maintenance intervals: weekly for wet pipe alarm devices, monthly for supervisory signal devices, quarterly for waterflow devices, and annually for all initiating devices.

The 2018 (or later) editions of NFPA 1, NFPA 72, and NFPA 101 are adopted by reference through the Georgia Fire Code; local amendments may be stricter than the state code.

Permits are required before installing or altering a fire alarm system; the AHJ must inspect and approve the installation before the system is placed in service.

Records of inspection and testing must be maintained and made available to the AHJ; the records must include the date, the tester, the device tested, and the result.

Plan review submittals must include a battery calculation, a voltage drop calculation, the device layout, and the sequence of operations; the AHJ may reject incomplete submittals.

Only listed and labeled equipment may be installed; the listing mark, the manufacturer, the model, and the compatibility listing must be verified for all initiating and notification devices.

The AHJ has the authority to require additional protection beyond the code minimum when the occupancy poses an unusual hazard; the AHJ decision is final and appealable per local ordinance.