Double sheetrock thickness and 3+gang mudrings

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MacG

Member
Greetings All,

I just got a question about a three gang box with a mud ring where the wall covering (double layer sheetrock) is greater than 15/16". Apparently they do not make a mud ring deeper than 13/16 for greater than two gang rings. The CBC requires no more than a 1/8" gap from device ring to FOF. I am unsure if this applies in the case of low voltage.

What are the solutions for this type of situation?

Thanks,

MacG
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
They make add a depth rings in metal or plastic.

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Box%20Extenders.jpg
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
What kind of 3 gang box? They usually make mud rings up to 2" deep. We use 1.25" mud rings for 3 gang rough house boxes on double layer Sheetrock.
 

curt swartz

Electrical Contractor - San Jose, CA
Location
San Jose, CA
Occupation
Electrical Contractor
What kind of 3 gang box? They usually make mud rings up to 2" deep. We use 1.25" mud rings for 3 gang rough house boxes on double layer Sheetrock.

Do you have any part numbers or links? I have never seen anything but flat and 3/4" rings for 3 gang and larger boxes.
 

curt swartz

Electrical Contractor - San Jose, CA
Location
San Jose, CA
Occupation
Electrical Contractor
If this is a rated wall the goof rings suggested would not maintain the rating of the wall. They do make deeper gang boxes so you could set the face of the box out 1/2" to make the 3/4" ring flush.
 

goldstar

Senior Member
Location
New Jersey
Occupation
Electrical Contractor
Sorry, I just realized you asked about 3-gang boxes and didn't know if you were using plastic or metal boxes. The metal ones seem to only be available in 1-gang.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
Sorry, I just realized you asked about 3-gang boxes and didn't know if you were using plastic or metal boxes. The metal ones seem to only be available in 1-gang.

There is no reason you can't use the plastic ones if the box is metal. The problem with the metal ones is they need to be grounded. I'll use a plastic one any day. :grin:
 

John120/240

Senior Member
Location
Olathe, Kansas
For a multiple gang box take the Arlingiton box extender & remove one side of

two box extenders for 2 gang. For three & four gang boxes do the same & just

use the top & bottom tabs for the middle locations.
 

cowboyjwc

Moderator
Staff member
Location
Simi Valley, CA
Is the two layers of sheet rock for sound or 2hr fire protection? If it's for fire protection the extension rings will not work as they are not rated. And you would need to be flush with the finished surface.

The 1/8" everyone talks about is around the ring not the depth that it can be inset, it can be inset 1/4".
 

MacG

Member
Good to know about the 1/8" and 1/4" difference.

We specify metal boxes in the commercial AV land. In theis partuicular instance there are 6 conduits from 3/4" to 1-1/4" for audio and video cables. Mixing the pastic mud ring and metal box in low voltage (under 70v) is code? This would be good to know.
 

cowboyjwc

Moderator
Staff member
Location
Simi Valley, CA
Good to know about the 1/8" and 1/4" difference.

We specify metal boxes in the commercial AV land. In theis partuicular instance there are 6 conduits from 3/4" to 1-1/4" for audio and video cables. Mixing the pastic mud ring and metal box in low voltage (under 70v) is code? This would be good to know.

And I should have specified that it can be inset a 1/4" if it's not a rated wall.
 

MacG

Member
So let me ask this: If it is a rated wall, what would work for a three gang and larger opening? You cannot set the box further out and cut out the first layer and there are no metal extensions. (2) 4-11/16" connceted by conduit gapped for two cover plates?
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
For a multiple gang box take the Arlingiton box extender & remove one side of

two box extenders for 2 gang. For three & four gang boxes do the same & just

use the top & bottom tabs for the middle locations.
John I have done that but that's a sloop job. Why do that if three gangs are available. Also the way you describe does not totally fill the void, IMO.
 
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