# EMT conduit in exterior concrete walls for romex wiring



## tk3000 (Oct 28, 2015)

Hello Folks, 
I am rewiring an old house (50s) with romex to have the flexibilitiy to run it outside conduits when necessary and to further protect the wire from creatures plus making it easier to upgrade in the future (not breaking drywall, etc). So, on the subject of emt conduit inside walls, I would imagine that given that the romex is  not requried to be in conduits whilst inside walls then the fact that the romex is not  inside a conduit all the way would then acceptable. The situation is depicted below: 



















In this particular situation the electrical box is inside the concrete exterior wall since there is a cavity in the concrete wall for the box only (and no indentation in the walls for any wire), so I can not connect the emt conduit to the box (yep, I reamed the conduit and also using bushings whenever the wires exit the conduit). Also, I don;t want to drill larger holes in the joists (at least not with the exterior walls) for the conduit, so the conduit does not go all the way to the attic; and once in the attic the wire should travel in conduits unless very impractical. Given that the wire is not travelling 100% of the time inside inside the conduits I assume that derating of the conduit is not necessary and that I can fill the conduit even to 100%. Also, I would rather not drill larger holes on the joist for the conduit. I just want to double check and make sure that this is acceptable?


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## Kabris (Oct 28, 2015)

Basically in this application the conduit wasn't really necessary since all you are doing is sleeving the wire inside the wall. As far as future use, nobody is ever going to pull another wire through that conduit after the sheet rock is put up.  To make the conduit practical you'd have to cut into the concrete, offset into the side of the box tight to the back, and drill through the exterior joist. Your other option would be to offset around the joist but have exposed conduit, which probably wouldn't look that great after the finished walls are put up. Sounds like a lot of work with little reward. I would leave it as is, and notch around the joist to run your romex.


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## CallMeVilla (Oct 29, 2015)

ROMEX inside conduit is not code.  Heating issues are the problem.  You can rip the covers off the ROMEX and run just the conductors (wires) and you would be fine.  Not sure why you want to run conduit anyway, unless you fear rodents ....  If you want a tough encased wire that does NOT have to be in a conduit, consider UF (underground feed) wire.  It would be easier and cheaper than conduit and stronger than ROMEX by itself.

Good luck


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## tk3000 (Oct 29, 2015)

CallMeVilla said:


> ROMEX inside conduit is not code.  Heating issues are the problem.  You can rip the covers off the ROMEX and run just the conductors (wires) and you would be fine.  Not sure why you want to run conduit anyway, unless you fear rodents ....  If you want a tough encased wire that does NOT have to be in a conduit, consider UF (underground feed) wire.  It would be easier and cheaper than conduit and stronger than ROMEX by itself.
> 
> Good luck



Yep, I know romex is not required to travel in conduits in most  situations. Heating issues would be compensated by derating the conduit, but NEC does not require one to derate the conduit unless the wire travels all the way inside a conduit; so I could even fill the conduit up to 100% in this situation, but I will lean on the side of caution and never fill to more than 60%. 

Indeed, I fear rodents but it would also make it easier to upgrade and add up in the future (I know this particular situation with exterior concrete walls is not ideal, but in most interior walls (2x4 studs) the conduit would go all way to the attic and there would no issue with clearance making it difficult for the wire to enter the outlet box). 

I will keep the underground feed in mind too! In fact, my next thread is about a pre-existing underground feeding to a detached garage. 

thks!


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## JoeD (Oct 29, 2015)

CallMeVilla said:


> ROMEX inside conduit is not code.  Heating issues are the problem.  You can rip the covers off the ROMEX and run just the conductors (wires) and you would be fine.  Not sure why you want to run conduit anyway, unless you fear rodents ....  If you want a tough encased wire that does NOT have to be in a conduit, consider UF (underground feed) wire.  It would be easier and cheaper than conduit and stronger than ROMEX by itself.
> 
> Good luck



NMB inside conduit is permitted in some situations. If it is just for protection and open on both ends it is fine.

Ripping the cover off NM cable and using the conductors in conduit is never permitted. The conductor are not certified for conduit use or any use outside of the cable.


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## tk3000 (Oct 29, 2015)

Kabris said:


> Basically in this application the conduit wasn't really necessary since all you are doing is sleeving the wire inside the wall. As far as future use, nobody is ever going to pull another wire through that conduit after the sheet rock is put up.  To make the conduit practical you'd have to cut into the concrete, offset into the side of the box tight to the back, and drill through the exterior joist. Your other option would be to offset around the joist but have exposed conduit, which probably wouldn't look that great after the finished walls are put up. Sounds like a lot of work with little reward. I would leave it as is, and notch around the joist to run your romex.



Yeah, you have a good point; but this is not a final situation I am still trying to approach in different ways and have the conduit travel through the joist or maybe having the conduit perfected aligned with a hole in the joist. And this situation is very specific due to the fact that it is an exterior concrete wall. The vast majority of the walls will not fall in this category and the conduit will go all the way to the attic. Still I have to verify whether or not the conduit could go all the way to attic (don't want to drill large hoses in important joist). At the bottom the conduit would be very close to the power outlet (there simply would be no fitting connecting the conduit to the outlet due to clearance issues in this case)


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## tk3000 (Oct 29, 2015)

JoeD said:


> NMB inside conduit is permitted in some situations. If it is just for protection and open on both ends it is fine.
> 
> Ripping the cover off NM cable and using the conductors in conduit is never permitted. The conductor are not certified for conduit use or any use outside of the cable.



I believe that in the interior of a  dwelling nm-b cable is permitted inside conduit in almost all possible situations. Nobody uses it inside a conduit mainly because it is fast, easy and cheap (and it is not required) to not use it inside conduits and otherwise simply staple it onto joists and studs.


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## Kabris (Oct 29, 2015)

With offsetting around the joist to get to the attic, you could box out the offset like they do with HVAC ducting, so nobody will ever see it.


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## tk3000 (Oct 30, 2015)

Kabris said:


> With offsetting around the joist to get to the attic, you could box out the offset like they do with HVAC ducting, so nobody will ever see it.



I will look into that. thks!


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