Fire rated walls and boxes

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chevyx92

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I know the IBC requires putty pads for boxes 24" or closer on opposite sides of the wall and if you exceed the 100 sq. in per 100 sq. ft.. My question what does it say or what do I need to do if you have an outlet at 18 AFF and then a wall sconce at 6' AFF in the same stud bay same side of wall? No I'm not over the 100 sq. in per 100 sq. ft.

One more question, is the 100 sq. ft of wall measured around corners?
 
mdshunk said:
If you are using wooden studs and not steel studs, the 24" separation doesn't apply.
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From the UL Fire Resistance Directory

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.

Metallic boxes located on opposite sides of walls or partitions shall be seperated by a minimum horizontal distance of 24in. This minimum seperation distance between metallic boxes may be reduced when "Wall Opening Protective Materials" (CLIV) are installed according to the requirements of their Classification.



Roger
 
roger said:
From the UL Fire Resistance Directory....
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That's great, but the IBC is the prevailing text, most of the time, and it has modified somewhat the general requirements of the Orange Book.
 
mdshunk said:
That's great, but the IBC is the prevailing text, most of the time, and it has modified somewhat the general requirements of the Orange Book.
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I don't think it has modified this requirement, I can post that tomorrow if someone else doesn't first. As a matter of fact I think it has strengthened this requirement.

Roger
 
roger said:
From the UL Fire Resistance Directory

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.

Metallic boxes located on opposite sides of walls or partitions shall be seperated by a minimum horizontal distance of 24in. This minimum seperation distance between metallic boxes may be reduced when "Wall Opening Protective Materials" (CLIV) are installed according to the requirements of their Classification.
Roger
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Then according to that(correct me if I'm wrong) then having a box above another box in the same stud bay doesn't matter as long as you are not over the 100 sq in per 100 sq ft? Right? And the 24" is only for horizontal measurements not vertical seperation???
 
It doesn't matter what the height is if the boxes face oppisite directions then you need the 24" of seperation. The requirement says horizontal and does not mention vertical.
 
chevyx92 said:
Then according to that(correct me if I'm wrong) then having a box above another box in the same stud bay doesn't matter as long as you are not over the 100 sq in per 100 sq ft? Right? And the 24" is only for horizontal measurements not vertical seperation???
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As long as it is on the same side of the wall I think you are right but, my agreement doesn't mean my interpretation agrees with the AHJ or inspector. :smile:

Roger
 
Now that I read the question again, let me see if I can answer it better. If the boxes are facing the same side, you can have them anywhere you want as long as the largest opening is not over 16 sq ins and you do not have over 100 sq ins in 100 sq ft.

If the boxes are back to back, the distince they are required to be seperated by 24" and one stud and you can close that distance if you use fire pads. How far they are seperated vertically does not matter.

Now for the catch. You have to have a STC (sound transmission control) rating of 50 or higher on the boxes which means a sound pad. The manufactures of the sound pad and the fire pad will tell you you can not stack them on each other. The fire pad people will tell you that they meet the STC, but if you look at their paper work it only shows a 49.

Though we did get some paper work from Hilti that showed a 55 STC for their fire pads.
 
cowboyjwc said:
Now for the catch. You have to have a STC (sound transmission control) rating of 50 or higher on the boxes which means a sound pad. QUOTE]

The STC thing is required for dwelling units. In commercial I do not think so.
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mdshunk said:
That's great, but the IBC is the prevailing text, most of the time, and it has modified somewhat the general requirements of the Orange Book.
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if the desinger is using a fire resistive design from the UL guide, then the rules Roger quoted will trump the ICC. Any deviation from the UL stuff and UL will not stand behind the listing of the design unless you pay big bucks to have them re-evaluate it. Even then it may not pass.
 
You are correct Larry. I may have read to much into the question, as I had just walked off of a senior apartment project, I just "assumed."

And that was the reason I gave that answer, because I never make mistakes.:grin:
 
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