Fire Alarm Installation Methods Study Guide

1. Codes, Standards & Documentation

NFPA 72: Fire Alarm and Signaling Code—main reference for installation, spacing, and supervision.
NEC Article 760: Covers wiring requirements for fire alarm circuits.
UL 864: Commercial FACUs; UL 985: Household FACUs; UL 1971: Visible notification appliances.
AHJ (Authority Having Jurisdiction): Interprets code and approves installations.
Annex in NFPA 72: Non-mandatory, informative material.
“Shall” = mandatory; “Should” = recommended.
Record of Completion: Must be signed and kept with system docs for final approval.
Manufacturer’s Instructions: Always follow for listed equipment.

Standard/Code	Application
NFPA 72	System design, installation, maintenance
UL 268	Smoke detectors
UL 1971	Strobe signals for hearing impaired
NEC Art. 760	Wiring/fire alarm circuits

FACU: Heart of the system; must be accessible, with 36” clear workspace in front.
Commercial FACUs: Listed under UL 864; household under UL 985.
Secondary power (batteries): Must support 24 hours standby, then 5 min alarm.
Dedicated branch circuit, breaker locked ON and labeled.
Panel must monitor for ground faults, loss of AC, battery trouble, and provide trouble/supervisory signals.

Power Problem	Action
AC Loss	Battery backup takes over, trouble signal activates
Battery won't charge	Replace if not recharged in 48 hours

Class A: Loop with return path; system works after a single open.
Class B: Single path; all devices after an open are inoperative.
Class X: Advanced; continued operation despite open/ground, uses fault isolation.
Class N: Ethernet/IP supervised communication.
IDC: Initiating Device Circuit—detects fires or troubles via detectors or manual pulls.
SLC: Signaling Line Circuit—addressable devices, device-level annunciation.
NAC: Notification Appliance Circuit—powers horns, strobes, speakers.
All circuits must be supervised for open, short, and ground faults; EOL resistor at last device on circuit.
Notification circuits require EOL resistor and ground fault supervision.

Smoke Detectors:
- Spacing per NFPA 72 and manufacturer’s listing (usually 30’ centers, reduce for high ceilings/obstructions).
- First detector on peaked ceiling: within 36” horizontally of the peak.
- Wall-mount: within 12” of ceiling.
Heat Detectors:
- Spacing per manufacturer, reduced for ceiling heights over 10’.
- Rate-of-rise detectors may false alarm if vent holes blocked.
Manual Pulls:
- Red unless otherwise required; maximum 48” height; within 5’ of exit, never more than 200’ travel to any pull.
- Must be on contrasting background and accessible to building occupants.
Duct Detectors: Supervise HVAC, must generate at least a supervisory signal if required by code.

Device	Spacing/Location
Smoke Detector	30’ centers (typ.), near peak/ceiling
Heat Detector	Per mfg/NFPA, reduce if ceiling >10’
Pull Station	Max 48” height, within 200’ of all exits

Strobes: UL 1971 listed, white for hearing impaired; must be visible to all intended occupants.
Horns/Speakers: UL 464 (audible alarms), minimum 75 dBA at pillow in sleeping areas.
Class A NAC: Continues to operate despite a single open; Class B loses downstream devices.
Voltage drop must not exceed 5%—use adequate wire size for NACs.

Appliance	Standard
Strobe	UL 1971
Horn/Speaker	UL 464

NEC Art. 760: Applies to all fire alarm wiring.
Separation: At least 6” from power wiring; 24” if parallel, cross at 90° if unavoidable.
Plenum spaces: Use FPLP or CL3P cable.
Minimum gauge: 18 AWG (commercial), per voltage drop tables and mfg.
Conduit: Where required by code or for protection from damage.
Secure, label, and support all cables—no splices in concealed spaces unless accessible for inspection.
Bend radius: At least 10x cable diameter.
Seal penetrations in fire-rated barriers with approved firestop.

All new systems require full acceptance testing and signed Record of Completion.
Semiannual/annual inspection and test required for devices, notification appliances, and power supplies.
Test switch simulates alarm or supervisory conditions for verification.
Sensitivity of smoke detectors: Must be within manufacturer’s published range.
Heat detectors: Test with listed heat source, not by hand.
Batteries: Monthly voltage, annual load test. Replace if cannot recharge within 48 hours.
Document all tests, repairs, and inspections.

Signal	Description
Alarm	Fire event, highest priority
Trouble	Fault that may impair operation
Supervisory	Non-fire condition (e.g. closed valve)