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EMT-protected Romex: sheathed or unsheathed

9364 Views 21 Replies 7 Participants Last post by  TwistedJoist
I am in the middle of upgrading some 1930s BX in my house. Actually the whole house is being re-wired. I am working with a licensed electrician, who has pulled the permit. He installed a new service drop, meter base, and 200 amp panel. I am running the cable and making up the boxes; he will make sure I do it correctly.

I've done a lot of reading about wiring techniques through various DIY books. Further, I have studied electricity and magnetism in college, so I have a theoretical background beyond most DIYs. I am the first to admit that this in no way means I have an in depth knowledge of the NEC, but I am learning.

My question is with regard to protecting Romex in EMT. In my stucco covered brick foundation basement, there are a couple of places where I need to run down the walls, where unprotected Romex is unacceptable. My electrician told me to protect it in EMT.

I've done some reading online and sense that most electricians, if they are running Romex in EMT for a short distance, seem to leave the sheathing on the cable. I have read assertions that the wires used in the stripped Romex are unlabeled THHN/THWN, but are unlisted with UL (or other appropriate listing agency). Because of the lack of labeling, most say stripped Romex conductors may not be run in EMT once stripped of their sheathing.

I took a look at the only Romex-in-EMT work in my house, which was performed by my electrician, and which supplies my heating system. This was for my reference, so I could do the work to the same standard. Regarding the run: it is a short run from a joist down to a thermal protection switch. It has the NM-EMT transition fitting at the end of the 1/2" EMT. The EMT makes a 90 deg. bend, drops down, and connects to a 4" utility box. What surprised me is that he stripped the sheathing off the Romex for the portion within the EMT.

Now, I can certainly see that Romex stripped of its sheathing would do a much better job of shedding heat than that in the sheathing. What he has done seems sensible, outside of the question of listing.

I am trying to decide if I should replicate what my electrician has done. It is his name on the permit and I feel I should follow his practice. On the other hand, if unlabeled conductors are a code violation, then I have a problem on my hands.

I guess I'm looking for some thoughts on this matter. I'm probably going to have to bring it up with him, but I don't want to come across as questioning his skills. Again, he's a licensed pro (a fact I have verified), has been in the field many years, and seems knowledgable. And as a bonus, he's willing to work with me, so I can do some of the grunt work to save some dollars. I didn't find many guys like that when I was looking for an EC. So I don't want to get on his bad side.

Any thoughts?
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The sheath cannot be removed as the cableis no longer a listed assembly.
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Hello Jim Port

Somewhere in my long winded post I said essentially that:
I have read assertions that the wires used in the stripped Romex are unlabeled THHN/THWN, but are unlisted with UL (or other appropriate listing agency). Because of the lack of labeling, most say stripped Romex conductors may not be run in EMT once stripped of their sheathing.
The problem is what do I do about it? Do I bring this up with my electrician, or do I just wait for the AHJ to catch it during inspection? My guess is the AHJ won't catch it.

Could one argue that since *some* of the sheathing is still on the Romex, it is still listed?
I am trying to decide if I should replicate what my electrician has done. It is his name on the permit and I feel I should follow his practice. On the other hand, if unlabeled conductors are a code violation, then I have a problem on my hands.
Did you get permission from your electrician to perform work under his permit? If not, you shouldn't touch it.

With respect to the Code, Romex may be run in EMT, and if it's for physical protection only (say, for vertical runs in an unfinished basement), you don't even need to worry about fill ratios.

And yes, it is a Code violation to strip Romex and run those conductors in EMT. I wouldn't be too worried about what's already been done, but I also wouldn't replicate the practice.
Did you get permission from your electrician to perform work under his permit?
Yes.

With respect to the Code, Romex may be run in EMT, and if it's for physical protection only (say, for vertical runs in an unfinished basement), you don't even need to worry about fill ratios.
It is for physical protection only, and not a "conduit sytem".

I guess I'm confused about the part in bold. Are you saying that because of the sheer physical size of a Romex cable, there's no way to exceed the maximum fill ratio of the EMT? Is this because fill ratios are based on the current carrying conductors' cross sectional area instead of the major-axis cross section of the whole cable, sheathing, conductors and all? Can you point me to where in the code?
Did you get permission from your electrician to perform work under his permit? If not, you shouldn't touch it.

With respect to the Code, Romex may be run in EMT, and if it's for physical protection only (say, for vertical runs in an unfinished basement), you don't even need to worry about fill ratios.

And yes, it is a Code violation to strip Romex and run those conductors in EMT. I wouldn't be too worried about what's already been done, but I also wouldn't replicate the practice.
Disagree on that, still need to maintain proper fill. One of the purposes of fill limits is to minimize overheating. Jamming a bunch of NM into EMT could cause a problem. Also could tear the cable sheath.

Butit appears I am wrong. Pharon post #7
Are you saying that because of the sheer physical size of a Romex cable, there's no way to exceed the maximum fill ratio of the EMT?
No.

Is this because fill ratios are based on the current carrying conductors' cross sectional area instead of the major-axis cross section of the whole cable, sheathing, conductors and all? Can you point me to where in the code?
Chapter 9 Tables

Notes to Tables
(1) See Informative Annex C for the maximum number of
conductors and fixture wires, all of the same size (total
cross-sectional area including insulation) permitted in
trade sizes of the applicable conduit or tubing.
(2) Table 1 applies only to complete conduit or tubing systems
and is not intended to apply to sections of conduit
or tubing used to protect exposed wiring from physical
damage.
Keep in mind that if it WERE part of a COMPLETE conduit system, and not just a section for physical protection, then fill ratios would apply, per note 9 and Table 1 of this same section:

(9) A multiconductor cable, optical fiber cable, or flexible
cord of two or more conductors shall be treated as a single
conductor for calculating percentage conduit fill area.
For cables that have elliptical cross sections, the cross sectional
area calculation shall be based on using the
major diameter of the ellipse as a circle diameter.
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Disagree on that, still need to maintain proper fill. One of the purposes of fill limits is to minimize overheating. Jamming a bunch of NM into EMT could cause a problem. Also could tear the cable sheath.
I agree with you with respect to good practice, but I don't see where the Code prohibits it. The only section I could find (see above) actually excludes it.
Would best practice be to place a j-box at top of length and then use THHN down to the box in the EMT?
Best practice would be to not overstuff a vertical section of 1/2" EMT with more than one 12/2 Romex even though the Code doesn't prohibit it. It's perfectly acceptable to use EMT as physical protection for Romex. Just use common sense.
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No need to switch the individual conductors. Just continue the cable down to the box. Use a bushing or fitting at the top of the sleeve.

From Mike Holt

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Is it possible that stripping the Romex sheathing for the portion within the EMT is a local exception to the NEC? I'm trying to figure why my EC would do this...
Call the local inspector and ask him the question, is what my electrician did acceptable ? You will get a yes or no answer. His is the only opinion that counts.

If he says yes, you don't have to worry about it.
Call the local inspector and ask him the question, is what my electrician did acceptable ? You will get a yes or no answer. His is the only opinion that counts.

If he says yes, you don't have to worry about it.
Yes, that is a possibility. But I'd rather not get my electrician in any hot water either.
The sheath cannot be removed as the cableis no longer a listed assembly.
I've read this many places on the interwebs. Do you have any idea of where I might find documentation that calls this out?
Another reason to leave the sheath on is so that at least a quarter inch of it can be in the box. I wouldn't challenge the EC on this. Tactfully ask him what his opinion is and see how big his ego is. Overall, I wouldn't worry about correcting what's already done.
I've read this many places on the interwebs. Do you have any idea of where I might find documentation that calls this out?
The NEC requires the testing, but I think you will have to dig thru the UL standards and procedures to find it.

Part of the same issue is the required wire markings. You can find them in NEC 310.120. They are required on every wire, or on every cable assembly. The wire size marking must repeat every 24 inches, and the other info every 40. In practice you tend to get an almost continuous marking that is repeating.

Romex and other cable assemblies are marked on the sheath only. Wires sold as individual conductors are marked on the insulation. If you remove the sheath from the cable assembly, you have wires that are not marked as required by the NEC.

If the inspector can't find the markings on the individual conductor insulation within 24-40 inches, he can have you remove it on that basis alone.
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The above post is replying to the quoted question and the generic subject, not necessarily on the problem in your original post.
Part of the same issue is the required wire markings. You can find them in NEC 310.120. They are required on every wire, or on every cable assembly.

Romex and other cable assemblies are marked on the sheath only. Wires sold as individual conductors are marked on the insulation.
Any one know why this is like this? Why not just use wire that is marked inside Romex? Is there a reason not too?

I do know that the Southwire sold at HD is marked THHN on the package, but the wire is marked THHN/THWN. Always wondered about this also.
The NM does does have or need the nylon coating of THHN , a cost savings.
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