Transitioning From Conduit to In-Wall

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Old 01-29-18, 04:10 PM
W
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Transitioning From Conduit to In-Wall

I am attempting to install a grid-tie PV system at my house in Utah. I think I have everything worked out except how to go from my A/C disco to my main panel. My A/C disco it outside, so I was going to bring it back into my garage with EMT, and then going to run against the wall in my garage until I get to my inner house wall. I was then going to drill a hole through both pieces of drywall to run the EMT through, but was then hoping to transition to in-wall wiring with Romex to my panel. I was hoping to find some sort of 1 gang new work box that I can bring the conduit into and transition to 10/3 Romex back to my panel that I will be backfeeding with a 30A breaker.

First off, is what I am even contemplating legal? And if so, is there anything that I can use to make this not so ugly?

Is there a better way to be doing this?

I can make a sketch of this if that helps.

Thanks for any info - Wil
 
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Old 01-29-18, 04:34 PM
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Just run the EMT into a 4x4 box while still in your garage, but close to the interior wall. Use that box to transition from wires to NM-B, then run NM into the house. You can always use a short piece of EMT to sleeve the NM for the few inches it may run in the garage into the wall. Then fire-stop caulk or spackle the hole to seal it.
 
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Old 01-29-18, 06:55 PM
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Zorfdt, thanks so much for the reply. Is the 4x4 box external to the garage wall's drywall? Can I do the same with an old work box instead of a 4x4 metal box? That way I can get a 90 degree conduit body into a plastic blank cover that I drill a hole out for the proper size for the conduit and then could caulk around whatever gaps there may be.

And is NM-B to code to run 240VAC in my crawl space without any conduit?

Thanks again, as I really, really do appreciate the help.
 
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Old 01-29-18, 07:21 PM
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NM cable is for dry locations only. Your crawlspace may be considered a damp area.
 
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Old 01-30-18, 06:13 AM
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I would be running in the floor joists, where there is already other 120VAC Romex being run, so hopefully that would be alright. Not sure if there was a different provision for 240 vs 120.

Does anyone have any input on the old work box?

Thanks - W
 
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Old 01-30-18, 07:34 AM
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The plan is OK for NM with 240V.

You can't use plastic boxes or fittings with EMT conduit, so I would say the old-work box plan is iffy. Not only would be box be obstructed by the conduit, but properly grounding the conduit would be hard. There are ways you could do it with a metal cut in box and a metal box cover, but a 4x4 box would be a much better option in my opinion.
 
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Old 01-30-18, 01:03 PM
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Just so I make sure I am on the right page, this is a 4x4 box?



And would it then be external to the drywall in my garage? Or is it internal, and as Zorfdt mentions, I would need to cut a wider hole to fit the conduit into it, and I would need to cover up that hole?

And I could put some sort of cover over it and complete my transition to NM inside of it? Sorry for my lack of knowledge on this, but I am slowly coming up to speed, and hope to help many neighbors make the jump to solar also.

A quick question about grounding the EMT. I am grounding the EMT at the point that the EMT connects to the flashed roof-mount enclosure via a ground bushing. As long as the rest of the boxes and conduit are all metal, is there a need to re-ground it again?
 

Last edited by Wil_L; 01-30-18 at 01:03 PM. Reason: Clarity
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Old 01-31-18, 10:46 AM
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Yes, that's the box you want. The box can be recessed into the wall, or surface mounted on the wall. It just depends how it's easiest to get the EMT into it and the Romex/NM-B out of it. The blank cover will of course need to be accessible regardless. Since you're in the garage, the decor isn't a huge issue, so surface mounting the box and conduit seems to be the easiest answer - but again, it's whatever is easiest.

When you securely attach the EMT to this box, the EMT will be grounded as will this box. Your NM-B ground wire would attach to a grounding screw at the back of this box, thus grounding your whole system. An additional ground wire through the EMT is optional (unless it's required for the solar setup - I don't know much about those setups).


I think you're over-thinking this part of the project. You can run wires inside EMT, and NM-B in protected and dry areas. You'll use a box like this to make any conversion from one to the other. You can really do the conversion anywhere that makes sense.
 
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Old 01-31-18, 12:53 PM
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Thanks for the reply.

I need to carry ground from my distribution panel all the way up to the solar panels on the roof, so in the EMT I'll have ground, 350V+ and 350V-.

I think the last question that hasn't been answered is if I am attaching the ground via a ground bushing to the up-most point of my conduit, do I need to worry about grounding the conduit or boxes anywhere else? If I am properly connecting/terminating the conduit to metal boxes (Inverter, A/C disco and 4x4) correctly, seems like all of it should be grounded.

Thanks again to everyone, as you have turned the part that I was most concerned about into something I understand decently now.
 
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Old 01-31-18, 01:29 PM
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do I need to worry about grounding the conduit or boxes anywhere else?
Yes. Ground must be bonded to every metal box where there is a ground wire. In an EMT conduit system, the ground wire is optional but if it is there it must bond to every box.

If the conduit system is continuous all metal, it can be grounded only at the source box/panel. The conduit and box system itself is then considered the ground. Devices (receptacles/switches) need to bond to the box via a ground screw and pigtail of green or bare wire.
 
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Old 04-17-19, 06:38 PM
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I know this is an old thread, but I need a bit more detail. I have a 4x4 box mounted on the drywall of a fire-rated garage ceiling. Conduit enters the left side, armored cable exits the right side and on the back (against the drywall) I have NM exiting the box through a cable connector, then through the drywall into the joist cavity. There is nothing around the NM as it penetrates the drywall.

I can reach the hole in the drywall - it is about 18" from the edge as I have yet to install more drywall. I would rather not move the box into the joist cavity because I need to get the conduit and armored cable to it neatly and outside the ceiling. Now the questions:

Do I need some kind of (conduit, connector, guard...) around the NM as it penetrates the drywall? If so, exactly what do I need and how to I terminate it (such as a short piece of conduit with a cable connector at the end after penetrating the drywall or ?)?

What kind of fire stopping do I need and where? (Sites discussing cable trays indicate fire stopping around the penetration AND filling the penetrating object with firestop caulk or putty. Would this also apply to my case or is something else in order?)

Thanks
D
 
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Old 04-18-19, 11:32 AM
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If I'm understanding correctly, the NM comes out of the back of the box directly through the drywall. In that case, it's not subject to damage, so doesn't need any additional protection. (If it came out the side and was exposed, then it would need something).

My understanding with fire stopping is that the box is sufficient as it covers the hole per code. But if it were my house, I would caulk around the cable the best I could to seal it to prevent airflow. Others will correct me if I'm wrong about the fire-stopping requirement.
 
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Old 04-22-19, 06:29 AM
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Firestopping/blocking is entirely regulated and inspected by the local building department of your city or county, so we can't really give an answer. Most all of us work in areas where you have a very picky inspector in one neighborhood and a lax one a couple miles over. The safest option would be to goop some fire caulk or foam around the NM before you screw the 4x4 box to the wall that way you've met the strictest standard they could enforce.
 
 

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