OR Fire Alarm Installer cheat sheet

A fire alarm system has four core functions: detect, signal, notify, and control; initiating devices detect, notification appliances signal occupants, and the control unit coordinates response.

Traditional (conventional) systems group devices into zones; addressable systems assign each device a unique address, allowing individual device identification and faster troubleshooting.

Supervised circuits monitor wiring integrity by passing a small current through the circuit; an open or short changes the current and triggers a trouble signal at the control unit.

Initiating devices include automatic detectors (smoke, heat, flame, gas) and manual pull stations; notification appliances include horns, strobes, speakers, and combination units.

Detection principles: ionization smoke detectors respond to small particles from flaming fires; photoelectric detectors respond to larger particles from smoldering fires; heat detectors respond to temperature rise or fixed temperature.

A zone is a defined area or group of devices; NFPA 72 limits the area per zone to 22,500 sq ft (2,090 m²) and requires each zone to be annunciated separately.

Alarm signals have priority over supervisory and trouble signals; supervisory signals indicate off-normal conditions such as valve closure or low air pressure; trouble signals indicate system impairment.

The alarm control unit provides power, receives signals, activates notification appliances, and may transmit signals to a supervising station or remote location.

NFPA 72 is the National Fire Alarm and Signaling Code; it covers design, installation, testing, and maintenance of fire alarm systems.

NFPA 70 (NEC) Article 760 covers fire alarm systems wiring; Article 760 Part I covers general requirements, Part II covers non-power-limited fire alarm circuits, Part III covers power-limited fire alarm circuits.

Oregon Fire Code adopts the International Fire Code with Oregon amendments; it references NFPA 72 for fire alarm system requirements and installation.

NFPA 72 requires smoke detector spacing of 30 ft (9.1 m) on smooth ceilings, with the first detector within 15 ft (4.6 m) of any wall or ceiling projection.

Heat detector spacing: 30 ft (9.1 m) for ordinary temperature-rated detectors on smooth ceilings; spacing reduces for high ceilings per NFPA 72 tables.

Manual pull stations must be mounted 3.5 ft to 4.5 ft (1.07 m to 1.37 m) above finished floor and within 5 ft (1.5 m) of an exit door.

Notification appliances must be installed per NFPA 72 Chapter 18; audible signals must be at least 15 dBA above ambient or 5 dBA above maximum ambient, whichever is greater, and at least 75 dBA at 10 ft (3 m).

NFPA 72 requires a record of completion (Form 1) and record of inspection and testing (Form 2); Oregon requires these documents for acceptance and periodic inspections.

Smoke detectors: photoelectric (scattered light) and ionization (ionization chamber); combination detectors use both technologies to reduce false alarms.

Heat detectors: fixed temperature, rate-of-rise, or combination; rate-of-rise responds to rapid temperature increase (typically 15°F per minute), fixed temperature activates at a set point (e.g., 135°F).

Duct smoke detectors are required in HVAC systems over 2,000 cfm (0.94 m³/s) to detect smoke in the air stream; they must be supervised and have remote test stations.

Projected beam smoke detectors are used for large open areas; they have a transmitter and receiver and are spaced up to 60 ft (18.3 m) apart with 30 ft (9.1 m) from walls.

Air-sampling smoke detection (ASD) draws air through pipes to a detector; used in high-value or difficult-to-access areas; pipe network design must follow manufacturer instructions and NFPA 72.

Initiating device circuits (IDCs) are supervised; conventional IDCs are typically two-wire or four-wire; addressable IDCs use a communication protocol over the same pair.

Class B initiating circuits do not survive a single open fault; Class A circuits continue to operate with a single open by using a redundant return path.

Manual pull stations must be addressable or zoned to identify location; they must be accessible, unobstructed, and within 5 ft (1.5 m) of exit doors.

Notification appliance circuits (NACs) are supervised; Class B NACs do not survive an open, Class A NACs survive a single open.

Audible appliances must produce a sound level at least 15 dBA above ambient or 5 dBA above maximum ambient (whichever is greater) and at least 75 dBA at 10 ft (3 m).

For sleeping areas, NFPA 72 requires a sound level of at least 75 dBA at the pillow or 15 dBA above ambient, and the signal must be distinct from other sounds.

Visible appliances (strobes) must be synchronized when multiple strobes are visible from a single location; synchronization prevents seizures and confusion.

Strobe candela ratings: 15 cd for rooms up to 20 ft x 20 ft; higher candela for larger rooms per NFPA 72 Table 18.5.5.4.1(a).

NAC voltage drop must be calculated to ensure the last appliance receives at least its rated voltage; use the formula VD = (2 x L x R x I) / 1000 for copper wire, where L is length in feet, R is resistance in ohms per 1000 ft, I is current in amperes.

NAC appliances are typically rated for 24 VDC; voltage drop should not exceed 10% of the rated voltage (2.4 V) to ensure proper operation.

Speaker circuits for voice evacuation must be supervised and have intelligibility requirements per NFPA 72 Chapter 18.

Fire alarm control units (FACUs) must be listed to UL 864; they provide power, supervision, and control for the system.

Primary power: 120 VAC dedicated branch circuit, labeled "FIRE ALARM CIRCUIT CONTROL," and must be protected against accidental disconnection.

Secondary power: sealed lead-acid batteries or other approved standby source; must be capable of operating the system for 24 hours plus 5 minutes of alarm (or 24 hours plus 15 minutes for voice systems).

Battery calculations: standby current (A) x 24 hours + alarm current (A) x 0.083 hours (5 min) = ampere-hours required; add 20% derating for aging and temperature.

Battery charger must be capable of recharging batteries within 48 hours (or 24 hours for voice systems) after a full discharge.

Power-limited circuits must be separated from non-power-limited circuits; use separate conduits or barriers, and label circuits as power-limited or non-power-limited.

NEC Article 760 requires fire alarm cables to be listed for the purpose; FPLR (riser) and FPLP (plenum) ratings are common; plenum cable must be used in environmental air spaces.

All wiring must be supervised; Class A wiring provides a redundant path, Class B does not; Class X provides isolation and redundancy for addressable systems.

Voltage drop formula for DC circuits: VD = (2 x L x R x I) / 1000, where L = one-way length in feet, R = resistance in ohms per 1000 ft, I = current in amperes; the factor 2 accounts for the return path.

Copper wire resistance (approx.): 14 AWG = 3.07 ohms/1000 ft; 12 AWG = 1.93 ohms/1000 ft; 10 AWG = 1.21 ohms/1000 ft; 16 AWG = 4.89 ohms/1000 ft.

Maximum allowable voltage drop on NACs is typically 10% of the rated voltage (e.g., 2.4 V for a 24 V system) to ensure the last appliance operates properly.

Battery capacity calculation: standby load (A) x 24 h + alarm load (A) x 0.083 h (5 min) = Ah; multiply by 1.2 for derating; for voice systems use 0.25 h (15 min) alarm.

Example: standby 0.5 A, alarm 2.0 A: 0.5 x 24 = 12 Ah; 2.0 x 0.083 = 0.166 Ah; total = 12.166 Ah; with 20% derating = 14.6 Ah; select 18 Ah battery.

NAC current draw must not exceed the power supply's rated output; calculate total appliance current and compare to NAC rating.

Voltage drop on IDCs is less critical because detectors operate over a wide voltage range, but must still be within manufacturer specifications.

Use a voltage drop calculator or spreadsheet to verify each NAC; if drop exceeds 10%, reduce load, increase wire size, or add a power booster.

Installation must follow NFPA 72, NEC Article 760, and manufacturer instructions; use listed components and approved methods.

Acceptance testing: verify all devices, circuits, and functions operate as designed; test initiating devices, notification appliances, and control unit functions; document on Record of Completion.

NFPA 72 inspection frequencies: monthly for control unit trouble signals; quarterly for batteries and chargers; annual for all initiating devices and notification appliances; sensitivity testing for smoke detectors within one year of installation and every two years thereafter.

Smoke detector sensitivity testing must be performed per manufacturer instructions; use calibrated test equipment or manufacturer-approved aerosol.

Testing must include: alarm activation, trouble signals, supervisory signals, notification appliance operation, and remote signal transmission.

Maintenance: clean detectors per manufacturer instructions; replace batteries every 3-5 years or as recommended; keep records of all inspections and tests.

Oregon requires periodic inspection, testing, and maintenance by a licensed fire alarm contractor; records must be available to the AHJ.

After any modification, addition, or repair, the system must be retested to ensure proper operation and documentation updated.

Oregon requires fire alarm contractors to be licensed by the Oregon State Fire Marshal; individual installers must hold a fire alarm installer certificate.

Permits are required from the local Authority Having Jurisdiction (AHJ) before installing or modifying a fire alarm system; submit plans and specifications for review.

Oregon Building Codes Division administers electrical licensing; fire alarm installers must work under a licensed electrical contractor or fire alarm contractor as applicable.

Continuing education: Oregon fire alarm installers must complete continuing education credits for license renewal; verify current requirements with the State Fire Marshal.

Contractors must carry insurance and provide proof of licensure; bonding may be required.

Inspections by the AHJ must be requested after installation and before system is placed into service; final acceptance requires Record of Completion and test results.

Oregon adopts NFPA 72 and the Oregon Fire Code; local amendments may apply; always check with the local AHJ for specific requirements.

Violations of licensing or permit requirements may result in fines, license suspension, or revocation; work without a permit may require removal and reinstallation.