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Mounting metal double gang electrical box to drywall


Derstig's Avatar
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01-10-18, 02:47 PM   #1  
Mounting metal double gang electrical box to drywall

I had a few situations where I had to install double receptacles (one GFCI one regular) in a 4 metal box on drywall where I had to install these on drywall surface using 1-1/4 drywall screws. 2 of these boxes are on ceiling and 1 is on wall.

The 2 on the ceiling are installed for one purpose only and that was to connect my jackshaft garage opener. They are on drywall ceiling by garage door. I have no conduit, the 12-2 NMB wire runs along side of the I beam connected to an existing junction box (all existing wiring are on ceiling and exposed without conduit, I only extended). I didnt want to install it on the thin side of the joist as its hard to find right middle of it and didnt want to risk of splitting it and having insecure connection.

The 1 other box is on a wall mounted in a similar fashion but this is on the garage/basement wall where there is no stud. Basically there is a double drywall on top of a 2x12 thats on its side.

I used 4 drywall screws on all these boxes. Is this okay?

 
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01-10-18, 04:49 PM   #2  
Having NMB wire exposed on the finished wall is violation of the code. This is because there is possibility of damage to the wire.
Cable on the ceiling is technically also not allowed since you have finished ceiling, but most inspector probably will say it is ok since they are unlikely to get damaged.
Just sleeve cable on the wall in a conduit or wiremold channel.

 
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01-10-18, 05:06 PM   #3  
You can't mount boxes just to sheetrock/drywall. They need to be attached to framing members.


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01-10-18, 05:11 PM   #4  
The NEC specifically allows NM cables to be run on the surface of the wall of ceiling. It cannot be subject to damage, but that is entirely subjective to the inspector.

You need to use anchors in the drywall to hold the boxes.

 
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01-11-18, 03:06 AM   #5  
What kind of anchors?

I did not use those tiny metal drywall screws for this but the black coarse threaded heavy duty ones. When I pull the box, it feels very secure and I used 4 screws not 2.

 
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01-11-18, 04:13 AM   #6  
Any drywall anchor will do. Even coarse threaded drywall screw is not strong enough.

 
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01-11-18, 05:06 AM   #7  
How about using toggle bolts?
Geo

 
Derstig's Avatar
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01-11-18, 05:13 AM   #8  
The box is actually 4-5 from the joist. At this point its probably easier to move it as is and use 2 screws instead of 4 and attach it to the small end of the joist. Is this acceptable?

 
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01-11-18, 05:41 AM   #9  
Screwing to the joist is the best.
Toggle bolt will be little over kill.

 
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01-13-18, 06:11 AM   #10  
I use then metal version of these by the hundreds: http://www.powers.com/pdfs/plastic/02345.pdf. They are quite secure in drywall. There are similar versions sold at all home/hardware stores.


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