Extension rings(boxes) How Many???

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Bill Marino

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It has always been my understanding that only 1-extension box or ring can be added to an existing box to increase it's volume. However in Art.314 I can not seem to locate anything on this. Recently I've come across some newer installations that have 2 rings or more added onto a preexisting 4x4x1.5" work box. Is this one up to the AHJ or one of those unwritten trade standards such as Blk.-Red-Blue is 208/120V?
 
Technically there is no limit, but one has to remember the free conductor rule.

For that size there must be 3” of free conductor outside the box. Wires would need to be extended in many cases.

Also connections must be accessible so a stack of them with connections buried at the bottom is gonna be a problem. That could be an AHJ call.

Someone will now post a rather infamous pic:
 
I once found a 4x4 box open in an attic. It was jam packed with conductors poking out in every direction. I put four extension rings and a blank cover on it to contain the mess.
 
jumper said:
Technically there is no limit, but one has to remember the free conductor rule.

For that size there must be 3” of free conductor outside the box. Wires would need to be extended in many cases.

Also connections must be accessible so a stack of them with connections buried at the bottom is gonna be a problem. That could be an AHJ call.

Someone will now post a rather infamous pic:
Click to expand...
And take into consideration whether or not the thing is flush in wall/ceiling, or if raceways enter any of the extensions.

If extensions can be as easily removed as a cover I don't think you need more then 3 inches of past the first "permanent" portion of the box.
 
kwired said:
And take into consideration whether or not the thing is flush in wall/ceiling, or if raceways enter any of the extensions.

If extensions can be as easily removed as a cover I don't think you need more then 3 inches of past the first "permanent" portion of the box.
Click to expand...

Code says past the opening of the box, adding the ring makes it part of the box.

If you get to use for additional volume, why would other rules not apply?
 
Those were the days, it ran quite long if I remember.
Was it before the new server ,02-03, I lost my original name back then.
 
Bill Marino said:
It has always been my understanding that only 1-extension box or ring can be added to an existing box to increase it's volume. However in Art.314 I can not seem to locate anything on this. Recently I've come across some newer installations that have 2 rings or more added onto a preexisting 4x4x1.5" work box. Is this one up to the AHJ or one of those unwritten trade standards such as Blk.-Red-Blue is 208/120V?
Click to expand...

The one box rule is a fallacy so it's not up to the AHJ to decide, add it to the list of electrical installation myths. Here's another that I've been hearing for 30 years, that you cannot actually use the KO's in an extension collar. :roll:
 
jumper said:
Code says past the opening of the box, adding the ring makes it part of the box.

If you get to use for additional volume, why would other rules not apply?
Click to expand...
One can also argue the extension is a raised style cover of some sort.

If you can still access conductors by removing extensions and inspector won't let that go, I have something to show him out back;)
 
kwired said:
One can also argue the extension is a raised style cover of some sort.

If you can still access conductors by removing extensions and inspector won't let that go, I have something to show him out back;)
Click to expand...

One could also argue that 8 single gang stacked extensions inside a sheet rocked wall may be a challenge to work on if you had to do that. Note: no disturbing the finish now.
 
jumper said:
One could also argue that 8 single gang stacked extensions inside a sheet rocked wall may be a challenge to work on if you had to do that. Note: no disturbing the finish now.
Click to expand...
I thought I mentioned it won't work if the box with extension(s) is flush mounted.

(add) unless you have conductors that extend at least 3" past the front.
 
How many extension???

How many extension???

Thanks for all of the reply's, the photo is a doozie. Ham & Egger electric at it's best! IMO anything beyond one extension ring means it's time to reevaluate the installation and install a new and larger box. "Neat and workmanship like manner" kind of stuff.
 
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