Fire proofing back boxes

Status
Not open for further replies.
Shockedby277v

Shockedby277v

Senior Member
Location
Michigan
I am currently working in a medical facility. Does anyone know what the code is for fire proofing back boxes IN walls with pads? Electrical code? Building code? Fire safety? Thanks in advance
 
Shockedby277v said:
I am currently working in a medical facility. Does anyone know what the code is for fire proofing back boxes IN walls with pads? Electrical code? Building code? Fire safety? Thanks in advance
Click to expand...

It is more convoluted. The codes, mostly the building codes, based on NFPA101 and the IBC, dictate standards that mus be met. Many of those define areas and how to divide those areas. For example a stairwell or a corridor that is placed in a defined way that is separated from the rest of the building with a 1 hour rated, or 2 hour rated wall. From a code perspective that is it. It is then up to the builder, Architect etc, to design and install the rated wall assembly. As such, listing agencies, predominately UL do extensive testing of construction methods with individual components to determine a "rating" to withstand as long as the assembly is built to that standard. Many of those standards require fire pads on boxes in some situations, in order to be listed. This doesn't even mean the wall won't withstand if it isn't built in that exact way. But is still must be built without deviation in order to pass muster. The other option would be to request, and probably pay for testing a different installation method. Here is a 100 page document that explains it better.

http://www.mhcea.org/Training moduleThrough Penetrations Feil 3-16-14 v3.pdf
 
As Lucky mentioned metal boxes have a two hour rating when located a minimum of 24" horizontally on opposite rated walls. You're allowed 16 square inches of penetration (translation 2 gang or 4" square hole in the wall). The 24" inch dimension can be reduced when using something like a putty pad either inside or or the outside of the box. Here's some info from UL regarding metal boxes:

Metallic Outlet Boxes (QCIT) for use infire-resistant rated assembliesAll UL Listed single- and double-gang metallic outlet and switchboxes with metallic or nonmetallic cover plates may be installedin bearing and non-bearing wood stud and steel stud wallswith fire rating not exceeding 2 hours. These metallic boxesare not required to be marked specifically as suitable for use infire-resistant rated assemblies.Metallic boxes located on opposite sides of walls or partitionsare intended to be separated by a minimum horizontal distanceof 24 in. This minimum separation distance between boxes maybe reduced when Wall Opening Protective Materials (QCSN)(commonly known as putty pads) are installed according to therequirements of their Classification.Putty pads other than those installed on the outer surfaces of ametallic box prior to installation of the wall are also available.UL Classified putty pads, also known in industry as box inserts,are for installation on the inside back surface of the box. Thereare also putty pads, known in industry as gaskets, available forapplication under the wiring device cover plate.
Click to expand...

http://www.ul.com/wp-content/uploads/2014/04/Ul_outletboxes.pdf
 
Status
Not open for further replies.
Top