4 Inch box recessed about 5/8" in ceiling

[DIYorBust]

On this project it looks like the electrician failed to properly account for the double sheetrock specified for the ceiling. In some areas it's relatively close, and in some it's really too far. The NEC seems to allow 1/4 inch of non-flammable material to be exposed. The sheetrock layers are 1/2" and there is a about 1/4 inch of cork in between the layers. One box is round, but most or octagon.

No problem, I thought. There is surely an extension ring for just this type of situation. It happens all the time when people tile walls, or sheetrock over plaster and such. But oddly, I have not been able to find such a product. It looks like there is a garvin/southwire 57111 which appears to fit the round box, but probably not the octogan box.

I can't be the first person to encounter this, what am I missing?

Thanks!

DIY

 

[Afjes]

Unfortunately it happens. Usually due to being too fast or not coordinating with the GC as to how thick the wall surface will be in the end. Thickness of sheetrock and or sheetrock and then tile on top etc.

There are box extensions for round and rectangular boxes available.

 

[Sponsor]

 

[DIYorBust]

They make extensions for outlet boxes, and they make a 1.5 inch extension for octagon boxes, but thay is too much to fit here. I can't seem to find an appropriate box extension.

 

[wwhitney]

Do you need a metallic extension? If not, there's

Arlington | Ceiling Box Extender

For set back ceiling boxes. Fits 3-1/2" and 4" round or octagonal boxes.

www.aifittings.com

For metal, there's this:

https://new.abb.com/products/7TBA126860R0006/obex-crt

Cheers, Wayne

 

[DIYorBust]

Thanks, and there's the challenge. I couldn't find the metal version anywhere to order. The plastic version looks good, but can I use it? The box is a metal box with type AC cable. At first I didn't think I could. It is in NYC which appears to be on the 2008 NEC, with amendments. I've never see anyone use a plastic box, and NM-Cable is not permitted in this building type.

But I can't find anything that prohibits the use of a plastic box if the connections can be properly made and made, ensuring the box and metal jacket remain grounded. I have no idea how you would do that with an ordinary blue box, but it would appear that since the connections are made to the metal box, I can't really see an issue.

2 questios some to mind:

1. If the box is fed from a side knockout rather than to top, do they want us to trim the extension around the entry? Seems like it should be okay to do.

2. Do I need extra long screws and is this okay to do?

Thanks,

Diy

 

[wwhitney]

What are you mounting on these octagon boxes? Would an octagon box mudring work for you?

0) Unless there's something in the building code prohibiting this bit of plastic, or some amendment to NYC's electrical code, the plastic extension would be fine. But NYC has some specialized codes, so you probably need to ask someone much more familiar with them.

1) Sure

2) Maybe and yes

Cheers, Wayne

 

[Reach4]

I would be surprised if NYC would allow plastic boxes or plastic conduit.
When you say "conduit" without saying "rigid", I expect you mean EMT. But for a lot of the country, when they say "conduit" they mean PVC or other plastic.

 

[DIYorBust]

When you say octagon mudring, do you mean something like this? https://www.menards.com/main/electr...l-box-mud-ring/737/p-1444451769202-c-6427.htm

Would it work? It says its for octagon boxes, so I guess it must fit, but would I be able to attach my light fixture to it? It seems to reduce the diameter between the screws. And yes, I'm attaching light fixtures, not planning on anything especially heavy or with a fan. I'm guessing the mud ring makes it the right diameter for a 3.5" octagon box. Do most fixtures come with a crossbar that will work with this?

 

[DIYorBust]

I would be surprised if NYC would allow plastic boxes or plastic conduit.
When you say "conduit" without saying "rigid", I expect you mean EMT. But for a lot of the country, when they say "conduit" they mean PVC or other plastic.

Thanks Reach4. First to be clear, there's no conduit involved in this issue. The boxes are fed12/2 type AC cable with a ground strip, but no grounding conductor in the cable, so the cable must generally connect to a metal clamp connector on a metal box to supply a ground for the box and any fixture with a grounding tail to the box, I'm not sure how this could work with plastic, but there may be specialized hardware for that. I think a metal mudring might be better in this setup since it would be stronger and not require such long screws.

 

[wwhitney]

When you say octagon mudring, do you mean something like this?

Yes, those are available in different rises and with both round and single gang openings.

Light fixtures that I have installed all use a mounting plate or cross bar with holes at various distances from center. So I assume that there are a small number of standard screw spacings, and that either style of mudring would hit one of those, and would work with most any light fixture mounting plate or cross bar. So it remains to be verified, but I'd say 98% likely.

Cheers, Wayne

 

[DIYorBust]

Thanks for the help guys! It looks like this problem isn't so bad. I got one of the round mud rings from the store. I was able to get it installed on one of the boxes, but it was somewhat more work than using a cover the same shape as the box because the sheetrock had to be cut to a round shape. Why don't they make one shaped like an octagon? Anyway, we'll probably need to mud up to the ring later to make sure there's no gap into the joist space. But I do have a sturdy all metal box, so no need to worry about code issues or screw failure.

I put a porcelain socket on it for now, which had screw knockouts for the smaller diameter ring so that was fine. May have to get some universal crossbars for the bigger fixtures. I mean, is it easier than just cutting the sheetrock and shimming down? Probably less things can go wrong this way. It's less sheetrock work, but not none really.