Backbox in fire rated wall

[Michael Harkey]

Imagine an ordinary backbox cut into the sheetrock of a one hour wall for a switch or a receptacle or fire alarm device. Since only one 'side' of the wall has the backbox, is that a penetration? Does the code require such installations of backboxes to be fire caulked?

 

[roger]

Yes, it is a penetration but doesn't necessarily mean anything has to be done if it's a single box except that it must be secured to a stud.

WALL AND PARTITION ASSEMBLIES

Metallic Eletrical Outlet Boxes

Listed single and double gang metallic outlet and switch boxes with metallic or nonmetalliccover plates may be used in bearing and nonbearing wood stud and steel stud walls with ratings not exceeding 2h. These walls shall have gypsum wallboard facings similar to those shown in Design Nos. U301,U411, and U425. The metallic outlet or switch boxes shall be securely fastened to the studs and the opening in the wallboard facing shall be cut so that the clearance between the box and the wallboard does not exceed 1/8 in. The surface area of individual metallic outlet or switch boxes shall not exceed 16 sq in. The aggregate surface area of the boxes shall not exceed 100 sq in per 100 sq ft of wall surface.

Roger