# How to bring Romex out of a block wall into a J-Box



## chollapete (Apr 18, 2008)

Hey, it's been a long time since I've been here. I'm in my 4th year of the IEC apprenticeship program, but except for a few months several years ago, all my work has been industrial and commercial.

Anyway, a buddy is remodeling his garage into an apartment and he asked me to do the electrical. The existing garage has block walls, with wood-frame above. The existing homeruns ran in concealed space above a 2x6 plate at the top of the block, in a joist bay. From there, they go through a hole in the plate into a cell of the block, down the wall inside the block, and out of a nipple into the back of the panel. 

For my new homeruns, I plan to bore a new hole in the cell next to the existing run and bring them out on the outside of the block wall into a 12x12x4 J-box. 

My question is how do I properly clamp the cables as they enter the box. There will be (6) 12/2s, (3) 10/3s, and (1) 14/2. Does the exception to strapping NM when fished through existing finished walls apply here? 

My first thought was to grout a 2-inch rigid nipple into the hole, securing it to the box with 2 locknuts, with plastic bushings at each end. This doesn't provide clamping. 

If I was going into a 4-square, I would use NM connectors with no more then 2 cables in each connector. Do I need to put a bunch of NM connectors in the back of the box? If I did, I can't see how I would sleeve through the block.

My last idea was to us a plastic, clamping bushing that snaps into a 2-inch hole knocked-out of the back of the box. This would fail to provide weatherproofing of the hole in the block, as grouting in a nipple would. However, I could grout in an oversize sleeve, then use a plastic, snap-in bushing that fits inside the oversize sleeve. That would give some clamping. Still not as weather-tight as locknuts or a Meyers hub, because there would be no seal between the sleeve and the bushing.

Hope someone can suggest the correct solution to this application.

One further note: I'm planning to mount a ground bar in the J-box, use lugs to terminate all the EGCs to the ground bar, then transition to THHN in EMT for the 2-1/2 foot run from the J-box to the bottom of the panel. All current-carrying conductors will be wire-nutted to THHN, but only a single, #10 EGC will be carried from the J-box to the panel, using the rule of continuing with the largest-size EGC. Does this sound kosher? 

Thanks,
Mark


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## backstay (Feb 3, 2011)

I don't put nm cable in block.


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## nhanson (Apr 17, 2010)

Having a hard time grasping how your talking about running your cable. if youre running on top of block then why not use EMT and pull wire?

Block wall go to the ceiling?

and possibly consider UF cable since it is block wall and can get wet.


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## watts77 (Dec 3, 2010)

i would just put a pvc male adater in the back of the box and just feed your wires in there. silicone around the hole and adapter will provide a weatherproof seal. no need to strap wires that are being fished down an existing wall


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## Dennis Alwon (May 9, 2009)

It seems clear you are an apprentice work without a license on a friends project. So.......

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