Extension rings on pull boxes

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aaronbailey52

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My electrical contractor installed 4" square boxes in the wall:

http://image.made-in-china.com/2f0j00deEtcIuqgCzh/4-Square-Electrical-Steel-Box.jpg

for use as pull/junction boxes.

Then he installed 1-gang mud rings on them.

Then he installed narrow throat extension rings:

http://www.menards.com/main/store/20090519001/items/media/Electrical/Raco/ProductMedium/187.jpg

on top of that. The entire assembly is used as a junction box and pull box, to transition from in-wall conduit to surface conduit. I'm, let's say, skeptical that this is good practice, but my co-worker is unconcerned. I'm concerned about the accessibility of the wires in the interior box and also about abrasion to wires on the lip of the throat of the extension ring. Any comments? By the time the installation has completed, some of the splices are about 6" deep in the wall through the 2.5" wide opening.
 
Those extension boxes are listed to be used as you've described. I've used them in the past and didn't see any problems with them.
 
Well, your first concern was the accessibility of the conductors. They are still accessible by removing the extension box revealing the plaster ring. The plaster ring is no worse than any installation of a receptacle or switch in there. The extension ring may be an overkill, but it certainly isn't making the conductors less accessible.

As for the abrasion, you probably shouldn't be pulling the conductor through the conduit inside the walls to the conduit outside the walls without either splicing it in the box or pulling the wire out of the inner conduit before pulling it into the external conduits.
 
aaronbailey52 said:
I'm concerned about the accessibility of the wires in the interior box and also about abrasion to wires on the lip of the throat of the extension ring. Any comments? By the time the installation has completed, some of the splices are about 6" deep in the wall through the 2.5" wide opening.
Click to expand...

I believe 300.14 is the code section that says the wires must be long enough to extend at least 3 inches outside the box opening....so there should be no reason for the splices to be 6" deep in the wall.
 
If that 1gang is all you have it is ok; but I would use a full open exring, why make it harder on us and I think the one he is using cost more.
 
sameguy said:
If that 1gang is all you have it is ok; but I would use a full open exring, why make it harder on us and I think the one he is using cost more.
Click to expand...

Agreed. Why use a narrow throat like that. Of course you can always do this.

ry%3D400
 
Why do you guys want him to use a 4 square box extension rather than doing it the way he did?

If you put a 4 sq box extension on a bracket box through sheetrock, the ko's are going to be half covered by drywall??? I always do the bracket box-mudring-extension box method when going through sheathing/drywall.
 
Cow said:
Why do you guys want him to use a 4 square box extension rather than doing it the way he did?

If you put a 4 sq box extension on a bracket box through sheetrock, the ko's are going to be half covered by drywall??? I always do the bracket box-mudring-extension box method when going through sheathing/drywall.
Click to expand...


I think we were responding to this type of ext. ring. I think this is for an extension from a recessed switch box to a 4" sq. Not really an extension for a 4 'sq.

187.jpg
 
Dennis Alwon said:
I think we were responding to this type of ext. ring. I think this is for an extension from a recessed switch box to a 4" sq. Not really an extension for a 4 'sq.

187.jpg
Click to expand...

I use those on mudrings. That's exactly what I was talking about using when I need to come through the wall with a bracket box.
 
Cow said:
I use those on mudrings. That's exactly what I was talking about using when I need to come through the wall with a bracket box.
Click to expand...

hmmmm - you're right about the KOs being 1/2 covered by the sheetrock - honestly never thought of the mudring extension before the 4 sq. extension to get the KOs out past the sheetrock !!:slaphead:
 
Do they make an extension ring for a 2-gang setup? That way you can still deal with the sheetrock but also have a larger handhole to pull the wires through?
 
1) use deeper box first
2) use Caddy bar to adjust the box flush to rock, do this with FA horn/strobes all the time
3) add exring
4) run pipe
5) keep it simple
 
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