Romex in conduit OK?

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LTLFTcomposite

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Apr 23, 2010
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4,780
Location
Central FL
We installed a clipper creek HCS40 this weekend at a friend's house using 6/3+G romex. The CC unit connects to a steel junction box where the 6/3 comes from the panel about 4 feet away. The panel is mounted in a raised frame off the wall that is sheetrocked. We bored a hole in the bottom of the frame where the 6/3 goes behind the drywall for about a foot before entering the bottom of the panel. For the exposed part we ran the romex through about 5 feet of (edit) 3/4" carlon (1" OD). The total length of the # conductors is about 8 1/2 feet from the 40A breaker to the wire nuts in the junction box.

Now I'm seeing some things that you aren't supposed to run romex in conduit. I'm having a hard time seeing why this wouldn't be OK, but if it isn't we'll want to correct it.
 
I read a long debate about this in an electrical forum. The short of it is, the romex can't be used in wet locations in conduit, but if you just want to protect it in a location where it is allowed by itself, it's ok. For wet/underground runs, you have to use UF cable in the conduit.

EDIT: I believe this was plastic conduit under discussion. I'm not as sure about steel, but if it's properly grounded and sealed it may be ok.
 
No problem running NM cable (Romex) in conduit. I didn't quite follow the description of how the NM cable is run, but:

If the conduit is used as a sleeve, i.e. at least one end of it is open behind some finished wall and the NM cable just comes out of it, then basically the only requirement is that the conduit is big enough for you to fit the cable in without damaging the cable.

If the conduit is a complete run from the panel to a box, then the conduit fill rules apply. I believe the allowable fill percentage is 53% for a single cable or conductor in conduit. You need to treat the cable as having a circular cross section of diameter equal to the largest diameter of the cable (i.e. the smallest circle in which the cable cross section would fit), and compare that area to the internal area of the conduit.

Cheers,
Wayne
 
wwhitney said:
No problem running NM cable (Romex) in conduit. I didn't quite follow the description of how the NM cable is run, but:

If the conduit is used as a sleeve, i.e. at least one end of it is open behind some finished wall and the NM cable just comes out of it, then basically the only requirement is that the conduit is big enough for you to fit the cable in without damaging the cable.

If the conduit is a complete run from the panel to a box, then the conduit fill rules apply. I believe the allowable fill percentage is 53% for a single cable or conductor in conduit. You need to treat the cable as having a circular cross section of diameter equal to the largest diameter of the cable (i.e. the smallest circle in which the cable cross section would fit), and compare that area to the internal area of the conduit.

Cheers,
Wayne

Excellent, thanks for the reply. Sounds like that gap between the end of the conduit and the panel makes it OK. The 6/3 romex fit easily into the 3/4 carlon, but I think it may have been more than 53%.

Sorry the description was a little vague. It's a finished garage with drywall, but the area where the service panel is "bumped out". So the EVSE, junction box and service panel are all on the same wall, but in order to get into the panel knockouts we needed to route into that bumped out area. So the carlon terminates inside the drywall bump out, and then the NM cable runs for about a foot behind the drywall where it enters the panel with a strain relief. The carlon is strapped to the wall.

Just curious, if the conduit did go all the way from the panel to the junction box, would I be able to correct it by just removing the romex jacket (and paper) to essentially convert it to three independent wires? (with an uninsulated ground wire)
 
LTLFTcomposite said:
Just curious, if the conduit did go all the way from the panel to the junction box, would I be able to correct it by just removing the romex jacket (and paper) to essentially convert it to three independent wires? (with an uninsulated ground wire)
The problem with doing that is that the individual wires within NM cable are almost never labeled, so while they are probably THHN/THWN, you can't actually know that. Better to just use THHN/THWN.

Cheers, Wayne
 
wwhitney said:
No problem running NM cable (Romex) in conduit. I didn't quite follow the description of how the NM cable is run, but:

If the conduit is used as a sleeve, i.e. at least one end of it is open behind some finished wall and the NM cable just comes out of it, then basically the only requirement is that the conduit is big enough for you to fit the cable in without damaging the cable.

If the conduit is a complete run from the panel to a box, then the conduit fill rules apply. I believe the allowable fill percentage is 53% for a single cable or conductor in conduit. You need to treat the cable as having a circular cross section of diameter equal to the largest diameter of the cable (i.e. the smallest circle in which the cable cross section would fit), and compare that area to the internal area of the conduit.

Cheers,
Wayne
Agreed , mechanical protection only ( required in Canada below 1.5 m) no de-rating necessary ( 2 current carying conductors) and no proximity to other cables.
 
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