Regarding Electrical Code 300-21

[info@triangle-electrical.]

We have a question regarding the electrical code 300-21 concerning firestopping. We have electrical boxes mounted on both sides of a fire rated wall. Do both boxes need to be protected with putty pads or firestop? If you could answer this question, it would be greatly appreciated.

 

[physis]

300.21 ...............Openings around electrical pentrations through fire-resistant-rated walls, partitions, floors or ceilings shall be fire stopped using approved methods to maintain the fire resistance rating.

It seems pretty straight forward to me.

 

[charlie b]

Seems to me that it is the wall that requires the fire stopping material, not the box(es) on either side of the wall.

 

[physis]

Seems to me that it is the wall that requires the fire stopping material, not the box(es) on either side of the wall.

I think you're right Charlie. I'm trying to find a way to stretch it to cover the boxes in order to maintain the fire rating but I don't think I can.

 

[Pierre C Belarge]

You mean something like this.

 

[physis]

Can you do that with plastic boxes? :grin:

 

[kroken]

don't they make fire rated box?

 

[480sparky]

don't they make fire rated box?

Yes.

 

[infinity]

don't they make fire rated box?

Metal boxes are not fire rated and would require the stuff that Pierre posted.

 

[wawireguy]

If I remember correctly.. it's if the boxes are within 2' of each other on opposing sides of the wall. That 2' number is foggy though. I believe it's a building code that you need to check into.

 

[nakulak]

In our area its withing the same stud space (ie. - put them on either side of a firestop or pay for the little blankets)

 

[cadpoint]

Regionally, it's a puddie padded box, other issues can be involved fast it can is also complimated by requirements of the NC Building Code, type and class of structure! An Odd but good example is that no box can be in a stairwell thats not associated with that stairwell, and is the same for elevators and there service room and all are required some/a fire rating coverage.

I do kinded side with Charlie, (wait he didn't say what I thought he said)! The fact is that the fire rating is gained by the application of gypsum board and that is from the face of board out, that a fire rating is gained.
But, if one penetrates it, your into the NEC Code, or respective trade codes!

There's also standard UL penetration details, if running through a fire rated wall. You can see some on your old drawings of the hotel in Chapel Hill, (if this the company that I think is asking!) Say Hello to Sue for me, and give Gary a call and bug him! :roll:

There's a search and many things all of UL, here

 

[Karl H]

So I take it, a "Cut-In" isn't compliant in a rated wall?

 

[LarryFine]

So I take it, a "Cut-In" isn't compliant in a rated wall?

Not unless it's attached to a stud. The drywall alone is not allowable for the box's support.

 

[Karl H]

Not unless it's attached to a stud. The drywall alone is not allowable for the box's support.

So yes or no? "The drywall alone is not allowable for the box's support."
In a rated wall? I'm just trying to clarify your statement because, you don't
attach a "Cut-In" box to a stud. The reason I ask is,because I've never
even thought about that until now, installing cut-in's in a fire rated wall
that is. I think I just learned a new error in my ways.

 

[wawireguy]

Lost track of this thread.. To be legal you need to apply your local building codes.

Imagined example:

I install a cut in box in a fire rated wall with 2 feet of another box on the opposing wall. My local codes say I have to fire stop this box. So now you have to use a approved firestop method for your install. So now you open your 3M or other fire stop application book and find a application that is appropriate to your install. If there isn't one then you contact 3M and have them engineer one for you. Probably there is a approved firestop for your application.

Pretty much you have to determine if fire stop is necessary then you have to install a approved firestop method for your electrical install.

 

[Karl H]

How do you "Putty-Pad" a metal cut-in box?

 

[wawireguy]

I believe there might be a application where you can seal the inside of the box.

 

[Pierre C Belarge]

If there is a fire rated wall, ceiling or floor, it would be a fire rated assembly.

Take a look at this manual, it is just one of many examples available


Cutting the surface is "membrane penetration" of the fire rated assembly. (such as a box installation)

Going through the fire rated assembly is a "through penetration" of a fire rated assembly. (such as a pipe or cable going through both sides of the wall)

Through Penetration

And one more product for boxes.

 

[physis]

Metal boxes are not fire rated and would require the stuff that Pierre posted.

I was just looking at 300.21 again and I don't see any need for a metal box to have a fire rating. Not to say I might not be missing something. (classic double negative). :grin: