Architectural · A-3T52E

Utility Box Spacing and Firestopping in Rated Partitions

Materials

Elements

Walls Partitions Waterproofing / Flashing Insulation Millwork / Casework Roof / Floor Openings

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Firestopping and horizontal separation requirements for electrical, telephone, and gas utility boxes installed in one-hour and two-hour rated or smoke partitions. Metallic outlet or switch boxes are limited to a maximum individual surface area of 16 square inches, with an aggregated surface area not exceeding 100 square inches per 100 square feet of wall area. Boxes located on opposite sides of rated fire or smoke partitions require a minimum horizontal separation distance of 24 inches unless separated by box pads or alternative UL-designed methods. Acoustical sealant for fire-rated assemblies or firestop sealant is applied all around the box maintaining a maximum one-eighth-inch annular space. Steel studs support the partition assembly as scheduled on the partition types sheet.

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