Fire Rated Walls in Residential Construction?

[JFletcher]

I cant seem to find the building codes that deal with this*. The question is this: can LV (open backed) boxes be used in walls that back up to a garage? In exterior walls? Would it matter if the garage is finished (sheetrocked) or not?

We dont deal with houses that are <5' from property line, and duplexes; not very often.

* I looked at 2009 Virginia Building Codes, and found this:

http://www.ecodes.biz/ecodes_suppor...pter 7_Fire and Smoke Protection Features.pdf

Section 705.5, page 5 (I cant copy/paste it from the site) is what got me thinking. Thoughts?

 

[GoldDigger]

Nice question.
Whether or not the Code allows it, I would not install an LV box like that in a fire rated wall.
The garage/living area wall will definitely have to be fire rated under most codes. Achieving that rating often requires that the wall on the house side of the garage be finished even if the rest of the garage walls are left open.

 

[JFletcher]

I agree, GoldDigger. My previous experience was with hotels, and almost every wall is rated in those, so we used regular 4"sq boxes for comm wire (despite them being a *bit* too small for mfg recommended sweep radius; never had a problem). I've never seen a rejection from the AHJ on using LV open back boxes for com wire in residential, but that's not to say it's right by code: many people kinda ignore LV (limited energy) as far as code goes.

I guess the question goes to this: in residential, what walls are commonly fire rated? If this varies significantly by location and local code, I'm in VA.

 

[kwired]

I agree, GoldDigger. My previous experience was with hotels, and almost every wall is rated in those, so we used regular 4"sq boxes for comm wire (despite them being a *bit* too small for mfg recommended sweep radius; never had a problem). I've never seen a rejection from the AHJ on using LV open back boxes for com wire in residential, but that's not to say it's right by code: many people kinda ignore LV (limited energy) as far as code goes.

I guess the question goes to this: in residential, what walls are commonly fire rated? If this varies significantly by location and local code, I'm in VA.

The fire rating of the wall may be looked harder at by the building inspector more so then by the electrical inspector, they may confer with one another if one of them has a concern though.

Single family dwellings - I'd say wall between the garage and the house and maybe between a room housing a gas furnace/water heater/boiler are about the only walls or even a floor/ceiling that are most likely to require a rating.

Multi family dwellings will often require a rating between units.



I believe most non metallic boxes have a rating marked on them, I know most fiberglass boxes I have ever seen do can't recall if the PVC boxes do. I doubt an open type LV ring has any rating though.

 

[jumper]

Fire rated walls, penetrations, and such for one and two family dwellings is covered in section R302 of the IRC.

VA adopts the IRC.

 

[north star]

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JFletcher,

Refer to Section R302 - Fire Resistant Construction,
Table on R302.1(1), in the 2012 VA IRC........See this
link:

http://codes.iccsafe.org/app/book/content/VA/2012_VA_Residential_HTML/Chapter%203.html



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[JFletcher]

ty Derek and north star for the IRC links.