Fire Cable: Code Red

1. What types of fire alarm cable are commonly used?

Fire alarm systems commonly use three cable types: FPL for general use, FPLR which is riser-rated for vertical shafts requiring flame resistance, and FPLP which is plenum-rated for air-handling spaces demanding stricter flame and smoke standards. Additionally, twisted pair, coaxial, and fiber optic cables can serve signaling or integration purposes but are not typically FPL-rated for primary fire alarm circuits. Verifying cable markings and UL listings is essential to ensure compliance with codes.

2. What codes govern fire alarm cable installation and survivability?

Installation and survivability of fire alarm cables are governed by key standards such as NFPA 72, which covers system design, support, and separation requirements; NEC Article 760, defining wiring methods and protection requirements; and UL 2196, certifying 2-hour fire-rated cable systems including supports and terminations. Local amendments and the Authority Having Jurisdiction (AHJ) may impose additional or more specific requirements.

3. What does survivability mean for fire alarm cable, and how do 2-hour fire-rated systems meet that requirement?

Survivability refers to the ability of fire alarm cables and associated components to remain operational during and after exposure to fire conditions. Cables must resist heat, physical collapse, and mechanical damage to maintain system integrity. UL 2196-compliant systems are tested rigorously to survive at least two hours under fire exposure, ensuring critical emergency systems like evacuation alerts continue functioning when most needed.

4. How often must fire alarm cable be supported in horizontal and vertical runs?

Proper cable support is essential for safety and code compliance. Horizontally, cables installed in conduit, raceways, or trays require support at intervals not exceeding 10 feet, with J-hooks or bridle rings spaced at no more than 5 feet. Vertically, cable supports must be placed at each floor level or at intervals not exceeding 10 feet, whichever is closer. Unsupported or sagging cables violate installation standards and can jeopardize survivability.

5. Can plastic fasteners be used for fire alarm cable?

Plastic fasteners are prohibited as sole support in fire-rated installations. They may melt or fail under heat, compromising cable survivability. Metallic fasteners are required and must be secured per code to maintain integrity during fire events

6. How should fire alarm cable be identified, and what should be done with abandoned cable?

Fire alarm cables should be identified clearly using permanent labels indicating circuit identification and connection points. While red-colored cable is preferred to visually distinguish fire alarm circuits, other colors are acceptable if properly labeled in line with NFPA 72. Any abandoned cables must be removed or clearly tagged to prevent airflow obstruction and avoid non-compliance with fire codes.

7. What are the rules for separating fire alarm cable from other wiring systems?

Separation requirements prevent electromagnetic interference and ensure safety. Fire alarm cables must be kept physically separated from power, data, and Power over Ethernet (PoE) cabling in accordance with NEC Article 760. Bundling fire alarm cables with other wiring is generally discouraged unless expressly permitted by code. In shared cable trays, physical barriers or approved separations are required. For Class A circuits, redundant pathways are mandated to maintain fault tolerance.

8. What are the rules for installing fire alarm cable in conduit versus open air?

Installation methods depend on cable type and environmental conditions. Plenum-rated cables may be installed exposed in air-handling plenums, while riser-rated cables require enclosure within vertical shafts or conduit. The use of conduit is dictated by cable ratings, environmental factors, and local code requirements, ensuring protection and code compliance.

9. What are the rules for penetrating fire-rated walls or floors with fire alarm cable?

All penetrations through fire-rated walls or floors must preserve the integrity of the fire barrier. This involves using UL-listed firestop systems and sealing materials to maintain the fire rating. Improperly sealed penetrations can compromise system survivability and violate fire safety codes.

10. What’s the correct bend radius for fire alarm cable?

The cable bend radius must comply with manufacturer specifications to avoid damage. Typically, shielded fire alarm cables require a minimum bend radius of ten times the cable diameter. Exceeding this radius risks conductor or shielding damage, which can impair cable performance and system reliability.

11. What gauge is required for notification appliances versus initiating devices, and how is voltage drop calculated?

Notification appliance circuits generally require 14 AWG or larger conductors to ensure sufficient current capacity, whereas initiating devices may use smaller 18 AWG conductors. Voltage drop calculations should follow Ohm’s Law, using the formula \( V_{drop} = I \times R \), where resistance is based on cable length and conductor properties. A voltage drop of 10% or less is typically recommended to maintain device operation within specifications.

12. Which fire alarm cables are suitable for hazardous, damp, or high-interference environments?

For corrosive, damp, or classified hazardous locations, cables with moisture-resistant jackets or metallic armor are necessary to protect against environmental damage. Explosion-proof fittings and cables rated for hazardous areas must be used where applicable. Shielded cables are recommended near equipment generating electromagnetic interference, such as motors or elevators, to preserve signal integrity. Verifying manufacturer environmental ratings and certifications is crucial.

13. Can fire alarm cable be spliced or repaired in the field?

Field splicing or repair of fire alarm cable is permitted only with UL-listed splicing kits and requires approval by the AHJ. Repairs must maintain the integrity of cable shielding and jackets. Documentation and verification of continuity are mandatory before the circuit is energized to ensure safety and code compliance.

14. How is fire alarm cable continuity tested before energizing?

Continuity testing involves megohm resistance measurements, loop resistance checks, and thorough visual inspections to confirm cable integrity. End-to-end continuity and proper terminations must be verified. All test results should be documented as part of the installation records prior to system activation.

15. What documentation is required for fire alarm cable approval, and how does the AHJ influence compliance?

Documentation necessary for fire alarm cable approval includes as-built drawings, labeling logs, inspection reports, and survivability test plans. The Authority Having Jurisdiction (AHJ) reviews these documents, inspects the installation, and enforces local codes and amendments. Maintaining thorough, accurate documentation is essential for final approval and ongoing compliance.

16. What training is required to install fire alarm cable?

Installers must adhere to NFPA 72 and local licensing or certification requirements. Training covers proper cable routing, termination, system programming, testing procedures, and compliance with applicable codes. Adequate training ensures installation quality and system reliability critical to fire safety.

17. Why must fire alarm cables be secured to prevent collapse into doorways and escape routes?

Fire alarm cables must be secured to prevent collapse into doorways, escape routes, and accessible windows because loose or falling cables pose a serious hazard during emergencies. In fire conditions, unsupported cable can sag, detach, or obstruct critical egress paths, increasing the risk of entanglement, injury, or delayed evacuation. Codes require that cables be fastened securely and routed away from exit corridors and openings to maintain clear passage and life safety. This is especially critical in surface-mounted installations or retrofit scenarios where cable exposure is higher. Proper support spacing and fire-rated fasteners help ensure cables remain in place under heat and stress.