In assembly occupancies of fire-rated construction, how much concrete is required to encase nonmetallic raceways?

In assembly occupancies that are constructed with fire-rated materials, it is essential to ensure that nonmetallic raceways are adequately protected to prevent fire spread and maintain the integrity of the fire-resistive construction. Encasing nonmetallic raceways in concrete provides that necessary level of protection.

The requirement to encase these raceways with 2 inches of concrete is based on fire safety standards aimed at preventing the escape of flames and limiting the transmission of heat. The 2-inch requirement is considered sufficient to provide a barrier that meets these fire resistance objectives, ensuring that the raceways do not compromise the fire-rated assembly.

This specification is critical in maintaining safety in assembly occupancies, where large groups of people gather, ensuring both compliance with the National Electrical Code (NEC) and the overall safety of the building's occupants in case of a fire incident.