Panel in fire rated wall

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Senior Member
I was just wondering something. When we install plastic boxes on fie rated walls, they have to be wrapped in 3M fire putty. If you installed a panel and did the same thing, would this be compliant?


Senior Member
I'm not sure what Carlton is refering to with their code reference. 314.17(c) in the 2002 NEC refers to protection agains abrasion on conductors entering boxes, not fire ratings.

The putty is required if you have two boxes in a single bay.

Any thoughts on my question about the panel? It seems like if you got sheets of the outty and encased the panel it would do the job, but I'm not sure how the putty is approved...Ie: is it approved specifically for boxes of a certain size.

Fred Bay

I should not speak to a residential application. But,

When installing electrical components in or through (conduit runs penetrating the wall) fire rated wall assemblies, you must use approved methods to maintain the rating of the wall.

It is very common on our projects to encounter "1 or 2 hour" walls. We regularly follow approved details which call for the use of fire caulking where conduits pass through a rated wall. We also cannot have outlet box openings larger than 16 sqare inches in certain rated walls, without using putty pads. There are also rules pertaining to "back to back" wall boxes, and the required seperation by a minimum distance and at least one stud bay. I could be more specific but it would lead to confusion.

I have been involved in another thread recently similar to this, and it seemed to spin sideways quite a bit. The best advise I could give you is to get the direction of the project architect and fire marshal.

By the way, I do not know of a putty pad that is rated for anything other than outlet boxes. Companies such as 3M publish the proper application of their products. Every application has to be "listed" and approved.

Hope that helps a little.


Senior Member
Contact your fire caulk, putty supplier. They should be able to provide a solution for your panel issue. And I don't think you need to putty pad every box opening in a firewall. On the project I'm working on(steel stud, metal boxes) you only have to putty pad the boxes that are within two feet of a opposite facing box. A box in one wall and the other box within two feet in the opposite wall. I would definetly check with your inspector first though.

Jim W in Tampa

Senior Member
Tampa Florida
I was given the job to fix a panel that was in already in a fire wall.I simply added another piece of 5/8 fire rated drywall behind it and boxed in the sides.Add fire calking and it passed.


Staff member
Simi Valley, CA
Most inspectors will allow the wrapping of a panel in a rated wall, but it is not a listed or approved assembly. As for the wrapping of the boxes to reduce the 24" of seperation, it is in the pad listing for the individual manufactures and it must be in the listing, because again it is not a method that you will find in any of the fire resistive manuals and not all of the manufactures allow it.


Senior Member
Burke, Virginia
dcspector said:
Per IBC 712.3.2 The Panel would exceed 100 sq. inches. As Jim mentioned all five sides around the panel would have to maintain the rating.

I quoted myself........ To maintain that rating is not puttypad, metacaulk, etc. It would have to be the USG rated assembly.
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