fire wall assembly

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lou32

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I have been asking some of the inspectors if there's a limit of a box size that can be install in a rated wall . Some told me that is control at 16 cu in max .Can that be possible?
 
I don't have the actual building code reference, but for some reason a limitation of 100 square inches of openings in 100 square feet of wall area seems to come to mind. Also, I remember something about 24 inch horizontal separation for membrane penetrations in opposite faces of the same wall construction.. Perhaps someone better versed in the applicable building codes could weigh in on this?

Pete
 
The FPN to section 300.21 gives us some guidance on where to look for this information.

The first place to start is your local building code. Section 712 of the IBC is goos example. The 16 square inch max is the allowance for NOT providing protection of the membrane opening when complying with the rest of the excpetion. But this section does not limit the size of a box.

Another place to look is in the UL Fire Resistance Directory. For example, UL QCIT.GuideInfo for Metallic Outlet Boxes can be found here:

http://database.ul.com/cgi-bin/XYV/...n=versionless&parent_id=1073991686&sequence=1

Spend some time on the UL website and in your building code. You will find there is alot of usefull information for electrical professionals there.
 
I read the link posted by Bryan, and I confused by the UL
wording:
"The boxes are intended to be installed so that the surface area of individual boxes does not exceed 16 sq in..."

If I am using metal boxes with metal mudrings, it sounds
like the "surface area" is determined by the box, not
the mudring, even though the cut in the drywall would
be determined by the size of mudring.

In other words, the link reads to me like 4-11/16 boxes
with mudrings are not OK because of the size of the
box. Is this correct?
 
rexowner said:
I read the link posted by Bryan, and I confused by the UL
wording:
"The boxes are intended to be installed so that the surface area of individual boxes does not exceed 16 sq in..."

If I am using metal boxes with metal mudrings, it sounds
like the "surface area" is determined by the box, not
the mudring, even though the cut in the drywall would
be determined by the size of mudring.

In other words, the link reads to me like 4-11/16 boxes
with mudrings are not OK because of the size of the
box. Is this correct?
Click to expand...

I would say no, that's not correct, the opening in the drywall cannot exceed 16 sq ins.

Now that's not to say that some other inspector may not call it the way you describe.

Now, there are some listed plastic boxes you can use that have a larger opening. Look at article 712 of the ICC Building Code.
 
The 16cu and 24" seperation seems to be rule in our area. Several Hotels /conds have at least 1 hour walls throuout.
Includes walls seperating living room and bedroom. We are allowed to place a drywall barrier above /below fire caulk the openings for the wires.
If the wall seperates a unit then you have to maintain the fire rating of the wall as if the panel was not in place. Fur the wall or if the wall is thick enough provide a drywall enclosure for the box.
 
cowboyjwc said:
I would say no, that's not correct, the opening in the drywall cannot exceed 16 sq ins.

Now that's not to say that some other inspector may not call it the way you describe.

Now, there are some listed plastic boxes you can use that have a larger opening. Look at article 712 of the ICC Building Code.
Click to expand...

What you are saying sounds logical. I actually
just finished a job using 4-11/16 metal boxes in
a firewall and it wasn't called out as a problem
by the inspector. It didn't occur to me at the time
that this could be an issue, because I assumed the
mudring size determined it. I just wanted to make
sure I wasn't off base.

Thanks.
 
We use fire rated pads here when we have a larger box. Anyone know how big a box you can use with a fire pad?
 
Sierrasparky said:
We use fire rated pads here when we have a larger box. Anyone know how big a box you can use with a fire pad?
Click to expand...

You can use what ever the inspector will allow, but you probably won't find anyone who will back it up as a fix, including the fire pad manufacturer.

Wrapping a panel is also not a listed assembly so, again, you might be on your own if anything were to happen. (We do approve that here).
 
cowboyjwc said:
You can use what ever the inspector will allow, but you probably won't find anyone who will back it up as a fix, including the fire pad manufacturer.

Wrapping a panel is also not a listed assembly so, again, you might be on your own if anything were to happen. (We do approve that here).
Click to expand...

May I ask if it why do you approve it if it could be wrong?
 
Sierrasparky said:
May I ask if it why do you approve it if it could be wrong?
Click to expand...

The same reason you use multiple fire pads on an opening that's to big, sometimes something is better than nothing, and if we make sure that they wrap it right and tape the joints just like they would do on any other assembly, it should work fine.

I will tell you that most contractors do not install the fire caulking per it's listing either, the problem is how do you really confirm it without removing it? I would say that fire stopping and penetrations are the number one write up in a rated building for us.
 
Here's partial info on 3M pads. Note this is for a 12inch box:

Type MPP+ moldable putty pads for use with max 12 by 4 by 2-1/2 in. deep flush device UL Listed Metallic Outlet Boxes installed with steel cover plates, for use in 1 or 2 hr fire rated gypsum board wall assemblies framed with min 3-1/2 in. wide steel studs and constructed as specified in the individual U400 or V400 Series Wall and Partition Designs in the Fire Resistance Directory.

Note that you have to use steel cover plates. Wall Opening Protective Material info can be found here:

http://database.ul.com/cgi-bin/XYV/...n=versionless&parent_id=1073991707&sequence=1

and here:

http://database.ul.com/cgi-bin/XYV/...n=versionless&parent_id=1073985106&sequence=1

Click on "View Listings" to get info from each manufacturer.
 
I dont believe the inspector has the authority to disregard the fire rated assemble rating by installing a typical none fire rated panel lets say and attempt to make it now rated with puddy packs ( while i have seen it attempted ) Puddy pcks have their specific application and we as inspectors cant waiver in the requirement....if they cant put the panel in a certain wall then they simply have to locate it somewhere else.
 
And for what it is worth....lol....the main problem I run into with SFD's (off topic a bit....sorry) is the confusion in the fireblocking requirements. In Richmond for example no one was maintaining the ratings once they drilled up and down.....they have to maintain fireblocking requiements so the electricians need to fill their holes between floors and such. (sorry to be brief...thumbing with moto Q )
 
radiopet said:
I dont believe the inspector has the authority to disregard the fire rated assemble rating by installing a typical none fire rated panel lets say and attempt to make it now rated with puddy packs ( while i have seen it attempted ) Puddy pcks have their specific application and we as inspectors cant waiver in the requirement....if they cant put the panel in a certain wall then they simply have to locate it somewhere else.
Click to expand...

What we were talking about with the panels is when you drywall around them and then install them in a wall cavity, much like they do for fire hose boxes and fire exstingusers, which are always in a corridor wall.
 
It may actually change from code to code and state to state (I've never done work outside Ohio, so I've never read code outside Ohio) according to the current OBC, it's

712.3.2 Membrane penetrations.
Membrane penetrations shall comply with Section 712.3.1 . Where walls or partitions are required to have a fire-resistance rating, recessed fixtures shall be installed such that the required fire resistance will not be reduced.
Exceptions:
1. Membrane penetrations of maximum two-hour fire-resistance-rated walls and partitions by steel electrical boxes that do not exceed 16 square inches (0.0103 m 2 ) in area, provided the aggregate area of the openings through the membrane does not exceed 100 square inches (0.0645 m 2 ) in any 100 square feet (9.29 m 2 ) of wall area. The annular space between the wall membrane and the box shall not exceed 1 / 8 inch (3.1 mm). Such boxes on opposite sides of the wall or partition shall be separated by one of the following:
1.1. By a horizontal distance of not less than 24 inches (610 mm);
1.2. By a horizontal distance of not less than the depth of the wall cavity where the wall cavity is filled with cellulose loose-fill, rockwool or slag mineral wool insulation;
1.3. By solid fireblocking in accordance with Section 717.2.1 ;
1.4. By protecting both boxes with listed putty pads; or
1.5. By other listed materials and methods.
2. 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 annular space between the wall membrane and the box shall not exceed 1 / 8 inch (3.1 mm) unless listed otherwise. Such boxes on opposite sides of the wall or partition shall be separated as follows:
2.1. By a horizontal distance of not less than 24 inches (610 mm);
2.2. By solid fireblocking in accordance with Section 717.2.1 ;
2.3. By protecting both boxes with listed putty pads; or
2.4 By other listed materials and methods.
3. The annular space created by the penetration of an automatic sprinkler, provided it is covered by a metal escutcheon plate.

and

712.3.1 Through penetrations.
Through penetrations of fire-resistance-rated walls shall comply with Section 712.3.1.1 or 712.3.1.2 .
Exception: Where the penetrating items are steel, ferrous or copper pipes, tubes or conduits, the annular space between the penetrating item and the fire-resistance-rated wall is permitted to be protected as follows:
1. In concrete or masonry walls where the penetrating item is a maximum 6-inch (152 mm) nominal diameter and the area of the opening through the wall does not exceed 144 square inches (0.0929 m 2 ), concrete, grout or mortar is permitted where it is installed the full thickness of the wall or the thickness required to maintain the fire-resistance rating; or
2. The material used to fill the annular space shall prevent the passage of flame and hot gases sufficient to ignite cotton waste when subjected to ASTM E 119 time-temperature fire conditions under a minimum positive pressure differential of 0.01 inch (2.49 Pa) of water at the location of the penetration for the time period equivalent to the fire-resistance rating of the construction penetrated.

So, if you have an architect you work with, it may be worth asking them to look it up in your local building code.
 
I'm well aware of what the code says.

You actually just build it like you would any alcove or closet in a corridor.

The better designers will simply build a closet and surface mount the panels in there and it saves a lot of headaches later.

Now, what the code says about using fire pads to reduce the 24" of seperation is simply out of the manufactures paperwork. When you do that on walls seperating units how do you get your sound rating? There is no fire pad that meets the required sound rating And neither the sound pad nor the fire pad manufactures will allow you to put them over each other.

Some times a fix just creates another problem.

The parts about the rock wool, two pads and the fire blocking are new to this code cycle, at least here.
 
cowboyjwc said:
I'm well aware of what the code says.

You actually just build it like you would any alcove or closet in a corridor.

The better designers will simply build a closet and surface mount the panels in there and it saves a lot of headaches later.

Now, what the code says about using fire pads to reduce the 24" of seperation is simply out of the manufactures paperwork. When you do that on walls seperating units how do you get your sound rating? There is no fire pad that meets the required sound rating And neither the sound pad nor the fire pad manufactures will allow you to put them over each other.

Some times a fix just creates another problem.

The parts about the rock wool, two pads and the fire blocking are new to this code cycle, at least here.
Click to expand...

John, sorry quoted your entire post and for a reason........I agree....I have nothing else to say.
 
In the past when fire walls were an issue, we would usually build a stud wall on one side of the fire wall so we wouldn't have to worry running anything through the firewall. But, that might be out of your scope of work.

Your mini closet idea sounds pretty good, except you would have the penetrations through the drywall for your conduit.

You could use a 3M or Hilti putty or firecaulk that has the same hourly rating as the wall.

You may want to talk with the owner to see if they're okay with the mini closet idea and cost, then take it to the AHJ.

I can't remember what number(s) they are, but there are also UL listing for penetration ratings. If there is a project Architect / Engineer you may want to ask what his spec for penetration fire rating is.

I hope this helps.:smile:
 
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