Extinguish the Flames: The Installation and Use of Fire-Resistive Cable Systems

National Electrical Code (NEC) Panel 3 established the new Article 728 in the 2014 NEC. It deals with fire-resistive cabling systems, and it was marginally revised for the 2017 NEC. The article covers the installation of fire-resistive cables, fire-resistive conductors and other system components used for survivability of critical circuits to ensure continued operation for a specified time while under fire conditions as the NEC requires .

Fire-resistive cable systems provide two-hour fire protection for specific wiring systems, such as fire alarm systems (Article 760), emergency systems (Article 700), critical care and life safety branch circuits (Article 517), and critical operations power systems (Article 708).

Section 728.4 states, “Fire-resistive cables, fire-resistive conductors, and components must be tested and listed as a complete system, must be designated for use in a specific fire-rated system, and must not be interchangeable between systems.”

There are two informational notes in 728.4. Note No. 1 provides one method of defining the fire-rated system by testing the system to UL 2196 2012, Standard for Tests of Fire Resistive Cables. Note No. 2 states, “Fire-resistive cable systems are considered part of an electrical circuit protective system.”

This information was inserted into 728.4 based on the following UL Guide Information: “The ratings for these systems apply to the entire system assembly, constructed using the combination of components and materials specified in the individual system as tested.”

Components are not intended to be interchanged between two different systems. In other words, the fire ratings are not assigned to the individual system components or materials. Rather, they are assigned to the overall fire-rated system. Based on the testing of the fire-rated assembly, electrical circuit integrity systems are intended to be fastened to a concrete or masonry wall, or a concrete floor/ceiling assembly. To ensure the complete electrical circuit integrity system will survive during fire and water-hose-stream exposure, the fire rating of the wall or floor/ceiling assembly must be equal to or greater than the electrical circuit integrity system rating.

Fire-resistive cable systems installed outside of the fire-rated rooms they serve, such as the electrical room or the fire pump room, are covered in 728.5(A) through (H). The installation instructions provided with the system listing cover all other installations. Section 728.5(A) covers mounting by stating the fire-resistive cable system must be secured to the building structure in accordance with the listing and the manufacturer’s installation instruction.

As stated in the UL test guide information and in 728.5(B), these systems must be supported in accordance with the listing and the manufacturer’s instructions since the supports are critical for the system’s survivability. Each system will have its own support requirements. Raceways and couplings are covered in 728.5(C), and the requirements apply where fire-resistive systems are listed to be installed in a raceway but only where the raceway enclosing the system as well as any couplings and connectors that are part of the raceway are listed as part of the tested fire-rated system.

In addition, the raceway fill for each fire-rated system must not be greater than permitted in Table 1 of Chapter 9. The heat transfer may be different for raceways with different fill than the tested assembly.

Cable trays used as part of a fire-resistive system shall be listed as part of the fire-rated system, based on 728.5(D). In accordance with 728.5(E), boxes used as part of the fire-resistive system must be part of the listed system and must be secured to the building structure independent of the raceways or cables listed in the system. Any pulling lubricants used with the fire-resistive cables installed in raceways must be tested as part of the assembly to ensure the lubricant doesn’t change the fire resistivity during the testing. Based on 728.5(G), cables and conductors installed in vertical raceways shall be supported in accordance with the testing and listing of the fire-resistive cable system. Lastly, only splices part of the assembly listing can be used and they must have manufacturer’s installation instructions.

Fire-resistive systems installed in a raceway requiring an equipment grounding conductor must use the same fire-rated cable described in the system, unless there is an alternative listed with the system and must be marked with the system number. The fire-resistive system cables and conductors must be surface marked with the suffix FRR (fire-resistive rating), the circuit integrity duration in hours, and the system identifier. Ensure compliance with Article 728 when bidding and installing the job.

About the Author

Mark C. Ode

Fire/Life Safety, Residential and Code Contributor

Mark C. Ode is a lead engineering associate for Energy & Power Technologies at Underwriters Laboratories Inc. and can be reached at 919.949.2576 and Mark.C.Ode@ul.com.

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