Question: What is the fire rating of steel conduit/EMT?

Answer: Steel conduit and tubing are considered noncombustible by the building codes. They do not have fire ratings. This question is usually asked relative to the penetration of a fire-rated assembly or use in an emergency circuit, fire pump, or mass transit vehicle (see Question 4 for information on NFPA 130 “Standard for Fixed Guideway Transit and Passenger Rail Systems”). The NEC does not require these thermal protection methods where conduit is installed in a fully sprinklered building.

1.) Penetrations

The NEC and building codes require the sealing of openings around raceways that penetrate a fire rated assembly. This requirement is to prevent smoke, gases and flames from migrating from one area to another. The NEC words in 300.21 are “not be substantially increased”, don’t know if we want to use that instead of “prevent.” There are many listed penetration fire-stopping systems that can be used to seal openings; the listing instructions should be strictly followed. Most building codes permit the openings around galvanized steel RMC, IMC and EMT in concrete or masonry to be filled with cement, mortar, or grout. However, since local codes sometimes vary, these requirements should be checked prior to installation.

2.) Emergency circuits (NEC 700.10(D)(1) and Fire Pump Circuits (NEC 695.6(A)(2)(d)

Prior to installing these circuits, the NEC and local or state code requirements should be reviewed. Steel raceways withstand fire (see Question 4); however, ordinary conductor insulation may be compromised when exposed to elevated temperatures, and a short circuit can be created. This is the reason for special protection of emergency and fire-pump circuits. Methods of fire protection include enclosing the raceways in a fire-rated enclosure, embedding them in concrete, wrapping them with a listed wrap system for protection from fire, or installing them as part of a listed Electrical Circuit Protective System. The UL Fire Resistive Directory contains information on listed fire-rated assemblies that include steel conduit and EMT. It is the entire assembly that has the fire-rating, not the individual component.