Fire Alarm Cable, Conduit, and Circuit Takeoff

FDAS wiring quantities come from the device layout plus a routing assumption. The complication is where the code demands fire-rated (survivable) cable.

Circuit types to measure

• SLC (signaling line circuit) — the addressable loop connecting detectors, modules, and call points.
• IDC (initiating device circuit) — conventional detector/call-point zones.
• NAC (notification appliance circuit) — horns and strobes.
• Interface wiring — to the fire pump, elevators, HVAC shutdown, magnetic door holders, duct detectors.

Length allowances

• Ceiling-to-device drop: ~3 m for wall devices, ~0.3 m for ceiling devices.
• Route along corridors and structure, not straight lines.
• Class A (loop return) circuits roughly double the wire versus Class B.

Fire-rated cable

Standard FPLR/FPLP or 1.5 mm² THHN in EMT is used for most circuits. Circuit integrity (CI) / 2-hour fire-rated cable is required where the code demands survivability — typically the pathway to notification appliances in high-rise, to the fire pump, and between the FACP and remote command equipment. Identify those runs separately; the cable is several times the cost.

Conduit and boxes

• EMT for all exposed and most concealed FDAS wiring (dedicated — not shared with power).
• Junction and device boxes at each device and pull point, painted red or labelled “FIRE ALARM”.
• End-of-line resistors/modules — one per conventional IDC and NAC.