Sierrasparky
Senior Member
- Location
- USA
- Occupation
- Electrician ,contractor
I was wondering how a Carlon blue cut in box B114r can claim 2 hour fire rating. I thought you cannot float a box on the drywall in a rated wall.
I worry about this stuff too but dismiss it as too much time on my handsI was wondering how a Carlon blue cut in box B114r can claim 2 hour fire rating. I thought you cannot float a box on the drywall in a rated wall.
Difference is a. YES I know thatnail on box is fastened to a framing member either wood or steel
How can it be listed as such if it is only secured by drywall.
UglyIn all honesty I just run add on circuits on fire rated walls in wire mold so I don't have to worry about it, new construction I follow code for spacing
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But how does nailing it to 2x4 make that penetration fire rated. It is still the same box material except one is mounted to the 2x4 with sheetrock around it one is mounted on the sheetrock.
I was wondering how a Carlon blue cut in box B114r can claim 2 hour fire rating. I thought you cannot float a box on the drywall in a rated wall.
It is ugly, but you need to maintain a minimum 24 inches spacing for fire rated walls if you can meet the spacing requirements then by all means do it, if you can't wiremold is an ugly solution like the girl in the bar at closing timeUgly
From the UL Fire Resistance Directory
WALL AND PARTITION ASSEMBLIES
Metallic Electrical Outlet Boxes
Listed single and double gang metallic outlet and switch boxes with metallic or nonmetallic cover 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.
I don't have time to look anything up as far as non metallic boxes are concerned at the moment, but here is what UL says about Metallic boxes in rated walls.
Roger
Ther is quite a bit of info but it follows suit with the metallic boxes -- I could not find anywhere in the UL directory that allows non metallic boxes to be supported by drywall -- are you sure the cut in is rated for 2 hrs
The exception in IBC 713.3.2 addresses this.
Membrane penetrations by listed electrical boxes
of any material, provided such boxes have been
tested for use in fire-resistance-rated assemblies
and are installed in accordance with the instructions included in the listing.
The majority of Carlon outlet boxes have a two-hour rating. We choice not to rate our old work boxes for two-hour assemblies for liability reasons. An easy well to tell if a box is rated for firewall construction is to look at the UL logo in the box (or in the area of the UL logo). If the box is marked with a 2-HR-* (* = W, C, F or WC) it is classified for two fire resistive assemblies.
I forgot your other question. Since cut-in boxes are not an option for existing walls, we would require a larger than the box opening next to a stud and patch in a piece of drywall using this Gypsum Assoc document. Do a Google search for repair of fire resistive walls and select a pdf entitled...
REPAIR OF FIRE-RATED GYPSUM PANEL PRODUCT SYSTEMS
The document above is the only guide to repair I ever found. You'll find all kinds of stuff on "repair to original rating" or "repair with listed products". Those documents or explanations never point you to resources.