Extending flush mount box into furred out wall options

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sw_ross

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Devices are currently flush mount in a block wall using typical masonry box.
They want to fur out this wall using 2x4's.

I'm trying to figure out a code-compliant way to extend the boxes out to the face of the finished surface.

The only thing coming to mind is to start with a 1-gang to 4-square extension ring, then add another regular 4-square box extension to that, then a 1-inch mud ring. That would get me out the 4 inches needed, but that's a PITA and not exactly code compliant.

Any other suggestions are welcome...
Thanks!
 
What's above the block and the new wall? Can you break into the old pipe and reroute to the new location?
 
sw_ross said:
The only thing coming to mind is to start with a 1-gang to 4-square extension ring, then add another regular 4-square box extension to that, then a 1-inch mud ring. That would get me out the 4 inches needed, but that's a PITA and not exactly code compliant.
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That's how I would do it. Actually sounds code compliant to me. Or you could get some four inch long arc shields fabricated.
 
This particular wall is a partition wall. It has receps on both sides that are all part of the same circuits as the side I'm working on. Conduit interconnects back and forth along a span of about 40 feet worth of wall. 12 receps on each side, 24 total, 4 circuits.

The ceiling is concrete slab, exposed. No drop ceiling.

I'm attempting to do this in a method that doesn't impact the receps on the other side. Not sure that's going to be do-able.
 
Coppersmith said:
That's how I would do it. Actually sounds code compliant to me. Or you could get some four inch long arc shields fabricated.
Click to expand...

North Dakota has a code addendum that only allows for one box extension unless approved by the AHJ. I'll probably give my inspector a call today and see what he has to say about it.
 
If it's being furred out four inches, you have room to run all new boxes and abandon the boxes in the block wall. Just disconnect them from power and route power to new boxes.
 
Coppersmith said:
If it's being furred out four inches, you have room to run all new boxes and abandon the boxes in the block wall. Just disconnect them from power and route power to new boxes.
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He won't need to disconnect power to the existing boxes. Just remove the receptacle, splice on some NM or MC and run to new boxes.
Besides, he said there were receptacles on the other side of the wall on the same circuit.
 
Little Bill said:
He won't need to disconnect power to the existing boxes. Just remove the receptacle, splice on some NM or MC and run to new boxes.
Besides, he said there were receptacles on the other side of the wall on the same circuit.
Click to expand...

You still need to have access to that j-box and not bury it in the wall.

I have thought about just extending out only the boxes that have home runs and then use either mc or NMB to finish out new boxes on that wall, abandoning the existing receps.
 
What is the reason for the 4” wall? Insulating?

Does it have to be 4”? Maybe you could talk them into flat 1x4’s and just use box extenders.

I don’t have any better ideas than what you have already come up with.


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brantmacga said:
What is the reason for the 4” wall? Insulating?

Does it have to be 4”? Maybe you could talk them into flat 1x4’s and just use box extenders.

I don’t have any better ideas than what you have already come up with.


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Click to expand...

Was also thinking about that. I think they mentioned insulation, but need to confirm that. Even if they did 2x2, or 2x4 flat it would make my job easier.

Thanks
 
3 1/2 inch deep box extension?

3 1/2 inch deep box extension?

I just got off the phone with the inspector asking him about options for this issue.
He said they do make a 3 1/2-inch box extension for this purpose (2x4 furring). Said he's used them before.

I've never heard or seen them. I called the supply house, they weren't aware of anything like that.

Anyone know of a 3 1/2- inch box extension? He said he'll let me use them under special circumstances.
 
Little Bill said:
He won't need to disconnect power to the existing boxes. Just remove the receptacle, splice on some NM or MC and run to new boxes.
Besides, he said there were receptacles on the other side of the wall on the same circuit.
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Would that splice be accessible?

Would a splice to short wires in the back of a now-6" deep box through a single-gang mudring be accessible? Practically no, but Code?

I've furred walls like this. I run 2x3's in the flat position, so the furring is only 1.5" thick. Unless you need to pass things through the studs like a normal wall. In which case I still use the 2x3's in the flat position and just run everything in the 2" space behind them (they are flush against the near side of a normal 2x4 sill laid flat at the bottom of the wall.) But that latter idea doesn't save anything on the current issue.
 
MAC702 said:
Would a splice to short wires in the back of a now-6" deep box through a single-gang mudring be accessible? Practically no, but Code?.
Click to expand...

I’d be concerned about that too.... I’d re-pull everything if they end up going a full 4”.


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brantmacga said:
I’d be concerned about that too.... I’d re-pull everything if they end up going a full 4”.


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If everything is re-pulled you should be able to demo the current device box in the block and extend conduit or flex to new stud boxes
 
david said:
If everything is re-pulled you should be able to demo the current device box in the block and extend conduit or flex to new stud boxes
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If it weren't for the need to continue supplying boxes on other side of wall, seems simpler to abandon and run new wiring in the new (furred out) wall.
 
sw_ross said:
You still need to have access to that j-box and not bury it in the wall.

I have thought about just extending out only the boxes that have home runs and then use either mc or NMB to finish out new boxes on that wall, abandoning the existing receps.
Click to expand...

MAC702 said:
Would that splice be accessible?

Would a splice to short wires in the back of a now-6" deep box through a single-gang mudring be accessible? Practically no, but Code?

I've furred walls like this. I run 2x3's in the flat position, so the furring is only 1.5" thick. Unless you need to pass things through the studs like a normal wall. In which case I still use the 2x3's in the flat position and just run everything in the 2" space behind them (they are flush against the near side of a normal 2x4 sill laid flat at the bottom of the wall.) But that latter idea doesn't save anything on the current issue.
Click to expand...

I wasn't thinking about the box not being accessible as I forgot the wall was block and would be hard to access the other side of the wall.
Unless there is a JB somewhere that feeds both sides of the wall, I think some type of extension box will be needed.
 
I haven’t been able to track down the box extension that the inspector was talking about. I’ll probably give him a call to get more specific info about what he was referring to (3 1/2-inch box extension).

Short of that, for estimating purposes I’ll plan for my original plan to use 2 box extensions and a mud ring.

The idea of re-pulling those home runs is a good idea to get plenty of conductor coming out of the box and make sure there’s no issue with existing conductors.
 
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