Understanding NEC Article 728: Fire-Resistive Cable Systems

NEC Article 728 establishes requirements for fire-resistive cable systems, designed to maintain circuit integrity and functionality during fire conditions. These systems are vital for critical operations like fire pumps and emergency power supplies, ensuring survivability in emergencies.

Scope of Article 728

This article applies to:

• Fire-resistive cables, conductors, and components installed to ensure continued operation of critical circuits under fire conditions.

Informational Note: Article 728 does not mandate the installation of fire-resistive cable systems but provides requirements if such systems are used. Common applications include fire pumps and Critical Operations Power Systems (COPS)​.

Key Requirements for Fire-Resistive Cable Systems

1. System Testing and Listing (728.4)
   • Fire-resistive cables must be tested and listed as a complete system.
   • Systems are non-interchangeable and must be used as designated for specific applications.
   • Testing standards include UL 2196, covering fire integrity for cables used in fire-resistive systems​.
2. Installation Guidelines (728.5)
   • Mounting and Supports: Cables must be secured and supported per the manufacturer’s installation instructions. Supports play a critical role in survivability during fire events.
   • Raceways and Couplings: Must be listed as part of the system and meet raceway fill limits per Chapter 9, Table 1.
   • Cable Trays and Boxes: Components like trays and enclosures must be listed and secured independently.
   • Vertical Supports: Cables in vertical raceways must meet the system’s specific support and listing requirements​.
3. Special Considerations
   • Pulling Lubricants (728.5(F)): Only use lubricants listed as part of the fire-resistive system.
   • Splices (728.5(H)): Allowed only if listed and installed per manufacturer’s instructions.
   • Equipment Grounding Conductors (728.60): Must use the same fire-resistive cable unless an alternative is specified in the system’s listing​.
4. Marking Requirements (728.120)
   • Cables must include the suffix “FRR” (Fire-Resistive Rating) and indicate the circuit integrity duration in hours.
   • Markings must also include the system identifier for easy identification and compliance​.

Applications

NEC Article 728 supports the survivability of critical circuits in:

• Fire Pump Installations: Maintaining power for firefighting equipment.
• Critical Operations Power Systems (COPS): Ensuring essential systems function during emergencies.
• Emergency Communications: Protecting vital communication links in fire scenarios.

Conclusion

NEC Article 728 provides essential standards for fire-resistive cable systems, focusing on system integrity, proper installation, and marking. These systems are a critical component in ensuring safety and functionality during fire conditions, particularly in high-risk facilities.