Covering Romex with EMT


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Old 01-17-20, 08:15 AM
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Covering Romex with EMT

I have a number romex lines on the ceiling of my garage that I would like to “upgrade” to not only make it safer but look more professional. I can either take all the wires out and use MC lite cable or I was thinking for the purposes of not wasting material (because overall its about maybe 25 feet of cable), simply fish romex into a 1/2” EMT.

To be clear, garage ceiling is finished. The romex runs are between ceiling mounted outlets and light fixtures and stapled to the drywall. There is no romex on the walls. For the wall mounted light switches, I fished romex from the ceiling behind the wall.
 
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Old 01-17-20, 10:00 AM
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You can sleeve NM-B (romex) in EMT. So that's a doable solution. I would probably use 3/4" or 1" and sleeve 2 or 3 cables in each. (You can't sleeve more than 3 in a single conduit though).

You could also box in the cables using some wood or drywall. Might be easier than rewiring each circuit. Leave a pull string for any future cable pulls.
 
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Old 01-17-20, 12:12 PM
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You can only sleeve romex if it not a complete system. If you have the EMT complete and fasten to boxes at both ends then NM cable is not permitted.
 
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Old 01-17-20, 01:21 PM
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What does complete system mean? There are two outlets on the ceiling. There is romex between them. Can I put the romex through the EMT and have EMT connect to box outlets?
 
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Old 01-17-20, 02:40 PM
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Using NM in a complete conduit system is not prohibited by the NEC. Doesn't make sense though to put NM in a complete conduit system.
 
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Old 01-17-20, 03:01 PM
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A complete system means the conduit connects to boxes at both ends.
Open ended conduit is not a complete system.
 
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Old 01-17-20, 04:24 PM
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There are two outlets on the ceiling. There is romex between them. Can I put the romex through the EMT and have EMT connect to box outlets?

Yes, you can do that, but I wouldn't, it isn't at all professional to pull NM cables in a complete conduit system although the NEC does not prohibit it. That being said, some jurisdictions will not allow a cable to be pulled into a complete conduit system either by amendment or by interpretation.
 
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Old 01-17-20, 06:57 PM
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A true sleeve (tubing open at both ends) doesn't work nicely with EMT because the EMT has to be grounded, and how would you do that?

If the EMT is connected to a box at one end, then you can convert from bare NM to NM-in-EMT with a special connector (and in certain cases, you can use a bushing instead of a connector). No problem, this is commonly done.

If the EMT is connected to a box at both ends, then like CasualJoe said, you can use NM but it's unprofessional.
 

Last edited by Luke M; 01-17-20 at 07:20 PM.
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Old 01-17-20, 08:17 PM
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I believe the NEC states EMT used only as a sleeve is not required to be grounded.
 
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Old 01-18-20, 04:34 PM
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I believe the NEC states EMT used only as a sleeve is not required to be grounded.
There's an exception for "short" sleeves. What counts as short? I have no idea.
 
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Old 01-18-20, 05:14 PM
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There's no definition of "sleeves" in the NEC. The NEC discusses raceways (conduit systems). Since it's not a raceway, those rules don't apply.
Instead, you're protecting the cabling where it's subject to damage. You could use wood, box it in, or use conduit. The NEC doesn't really specify what you can or can't do. The only exception is derating if the sleeve is more than 24".

So in a nutshell, you can sleeve NM-B cable for any length without running afoul of the NEC.
 
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Old 01-19-20, 02:52 AM
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There's a general rule (250.4(A)(4)) that metal that is "likely to become energized" (meaning, likely in the event of insulation failure) must be grounded. Surely that includes sleeves?
 
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Old 01-19-20, 07:29 AM
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I did some more reading and Luke, you are correct about "short" sleeves.

Paragraph 300.10 Exception 1: (appeared in 1999 edition NEC)
“short sections of raceways used to provide support or protection of cable assemblies from physical damage shall not be required to be electrically continuous.
Of course, "short" is defined by the local AJH
Here's an engineering article about bonding sleeves, if you're so inclined: https://www.csemag.com/articles/bond...nduit-sleeves/
 
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Old 01-19-20, 09:30 AM
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There's an exception for "short" sleeves. What counts as short? I have no idea.

That would be open to local interpretation by the AHJ.
 
 

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