Question about conduit and wire for new circuit in unfinished room

pete6032 · Apr 28, 2025

I am installing a washing machine and dryer in an unfinished basement with cement block walls. I want to run a dedicated circuit to these appliances. I want to put the outlet in the middle of the wall behind the machines, then run conduit up the wall to the ceiling joists, then run the wire through the joists back to the electrical box. I understand that typically you would run thhn wire through the conduit. The run of conduit between outlet and ceiling joists is about 5 ft. Do I need to go out and buy 5 feet of thhn wire to go in the conduit and then transition to romex to run it through the joists? Or can I just put the romex in the conduit? If I need to transition from thhn to romex, would I need to affix a junction box to the joist to transition?

sdifox · Apr 28, 2025

You run two Romex runs from two breakers to junction box. The dryer needs 220VAC while the washer just needs 110VAC. So you would have one dryer NEMA 14-30 socket, then besides it you can have a standard dual NEMA 5-15 socket.

All enclosed in conduits and boxes

Greenman · Apr 28, 2025

sdifox said:
You run two Romex runs from two breakers to junction box. The dryer needs 220VAC while the washer just needs 110VAC. So you would have one dryer NEMA 14-30 socket, then besides it you can have a standard dual NEMA 5-15 socket.

Don't need 220V if it's a gas dryer.

sdifox · Apr 28, 2025

Greenman said:
Don't need 220V if it's a gas dryer.

He didn't mention it's a gas dryer. And if it is gas it requires a plumber to run gas line.

Ken g6 · Apr 28, 2025

It is possible to get a 110V electric clothes dryer! They use a heat pump so they're more efficient, but they're still small and expensive compared to a 220V dryer. Random example:

Amazon.com

herm0016 · Apr 28, 2025

no. you don't. I am an electrician. You are allowed to run the Romex in the EMT as long as you have a go from fitting and the EMT is there for "mechanical protection" which is exactly your situation. run 10-3 for the dryer and 12-2 for the washer. always run a neutral and use a 4 wire plug. it is safer than a 3 wire and code requires the neutral in the outlet now. in a basement you will need a 2 pole 30 amp GFCI breaker for the dryer and a 1 pole 20 amp gfci breaker for the washer. match the brand and type of breaker to you panel. use metal boxes with the emt, proper connectors, and make sure to ground the boxes and outlets properly. my other advise is to never buy the cheapest option for outlets, always get a step or 2 up at least and always use the screws, not the push in connections. use wire nuts, not push ins unless its just lighting or some other low current situation.

go from fitting:
https://www.homedepot.com/p/Halex-1...sORjDo3l74h67I8CTLEaAlMzEALw_wcB&gclsrc=aw.ds

pete6032 · Apr 28, 2025

It a gas dryer I should have mentioned.

herm0016 · Apr 28, 2025

with gas, run 2 20 amp 110 circuits.

Greenman · Apr 29, 2025

herm0016 said:
no. you don't. I am an electrician. You are allowed to run the Romex in the EMT as long as you have a go from fitting and the EMT is there for "mechanical protection" which is exactly your situation. run 10-3 for the dryer and 12-2 for the washer. always run a neutral and use a 4 wire plug. it is safer than a 3 wire and code requires the neutral in the outlet now. in a basement you will need a 2 pole 30 amp GFCI breaker for the dryer and a 1 pole 20 amp gfci breaker for the washer. match the brand and type of breaker to you panel. use metal boxes with the emt, proper connectors, and make sure to ground the boxes and outlets properly. my other advise is to never buy the cheapest option for outlets, always get a step or 2 up at least and always use the screws, not the push in connections. use wire nuts, not push ins unless its just lighting or some other low current situation.

go from fitting:
https://www.homedepot.com/p/Halex-1...sORjDo3l74h67I8CTLEaAlMzEALw_wcB&gclsrc=aw.ds

Is there a length limit on the mechanical protection rule?

herm0016 · May 4, 2025

Greenman said:
Is there a length limit on the mechanical protection rule?

No, but it gets hard to justify after some length with inspectors. If you strip the jacket and use a go from, the wire is just thhn in the jacket and you can do whatever you want, because its not NM anymore, it's THHN.

some people will quote the 6 foot rule, but that's for metallic sealtite and other flexible metallic to use them as the ground vs running a ground wire. others will say 2 feet, but that is actually for conduit fill, if it's under 2 feet fill rules do not apply, you can jam as many wires as you want in the raceway.

Greenman · May 4, 2025

The inspectors where I did all my work just said no to romex through conduit, unless it was a simple sleeve through masonry or a fire wall. It rarely came up since all of my work was residential.

Red Squirrel · May 17, 2025

There seems to be some mixed info on this, but there are situations where I've done it anyway. Typically to get through tough locations to run wire, like above a bunch of ductwork where it's not feasible to hammer staples in because I just can't get a good angle to swing the hammer or can't physically get in far enough. I'll just run a conduit above that area so the wires can clear the ductwork or whatever other obstruction without drooping and potentially coming in contact with it. I also added a couple conduits going to my garage as it involved breaking up concrete so rather than deal with that each time I want to run a wire, I just did it once and got it over with and now I have a bunch of conduits to run any wiring I need.

Is it to code? I honestly don't know. Is it safe? I'd like to think so, it's not much different than running through the walls or through a raceway. If you were to do a very long conduit then I suppose heat build up could be an issue if you have a bunch of sheathed cables stuffed in there, but a short length just to get from A to B with both ends open, I don't think it's an issue.

Sukhoi · Jun 4, 2025

AFAIK you can run it and you can't strip it. It's only marked on the outer sheathing, hence no stripping. To size the conduit you have to consider the entire cross-section of the NM-B, and thus use larger conduit. I last calculated this a couple years ago, but know I ended up needing 3/4" EMT for 12/2 NM-B. Depending on loads you may also need to consider temperature rating since IIRC NM-B is only 60 °C and that can also cause upsizing requirements.

And yes you use @herm0016 's fitting as strain relief where the NM-B enters the conduit up at the ceiling.

herm0016 · Jun 7, 2025

Sukhoi said:
AFAIK you can run it and you can't strip it. It's only marked on the outer sheathing, hence no stripping. To size the conduit you have to consider the entire cross-section of the NM-B, and thus use larger conduit. I last calculated this a couple years ago, but know I ended up needing 3/4" EMT for 12/2 NM-B. Depending on loads you may also need to consider temperature rating since IIRC NM-B is only 60 °C and that can also cause upsizing requirements.

And yes you use @herm0016 's fitting as strain relief where the NM-B enters the conduit up at the ceiling.

I have never had an inspector get me on conduit fill when there is just one NM either 12-2 or 14-2 or 14-3 in a 1/2 EMT. conduit fill is really about heat in the cross sectional area and you will never have that issue with a 20 amp circ. I have also never had anyone question a time when we did strip it back, then it becomes THHN and the mechanical protection only rule does not apply and you treat it like regular raceway. All the resi stuff is spelled out in code, 15 amp on 14 gauge, 20 on 12, etc. it already includes a step on the derate table for fill, temp etc. Either way is totally safe. only caveat is that if you are using EMT as mechanical protection, the inside of the pipe will be rated at whatever environmental conditions exist on the outside of the pipe... eg. dry, damp, wet, or hazard zone xx location.

Actual ampacity of a 12 awg for example is 25 amps in both the 60C and 75C columns. 30 amps in the 90 degree column, which is the column used when doing any derate calcs when its THHN/THWN wire, the same stuff that is in NM cable.

Sukhoi · Jun 7, 2025

Oh I'm not saying there's anything unsafe, just that the fill amount and stripping back violate various sections of the NEC that a picky inspector could cite. Sure, very unlikely. The couple of electrical inspectors I've had to deal with weren't too bright anyway. Had one question why I had installed a 50 A breaker (with 6 AWG wiring) for a hardwired 40 A EV charger lol. Then he acted like of course he knew the code that an EV charge is a continuous load thus requiring 125% circuit capacity sizing.

Greenman · Jun 7, 2025

herm0016 said:
I have never had an inspector get me on conduit fill when there is just one NM either 12-2 or 14-2 or 14-3 in a 1/2 EMT. conduit fill is really about heat in the cross sectional area and you will never have that issue with a 20 amp circ. I have also never had anyone question a time when we did strip it back, then it becomes THHN and the mechanical protection only rule does not apply and you treat it like regular raceway. All the resi stuff is spelled out in code, 15 amp on 14 gauge, 20 on 12, etc. it already includes a step on the derate table for fill, temp etc. Either way is totally safe. only caveat is that if you are using EMT as mechanical protection, the inside of the pipe will be rated at whatever environmental conditions exist on the outside of the pipe... eg. dry, damp, wet, or hazard zone xx location.

Actual ampacity of a 12 awg for example is 25 amps in both the 60C and 75C columns. 30 amps in the 90 degree column, which is the column used when doing any derate calcs when its THHN/THWN wire, the same stuff that is in NM cable.

Are the actual wires in Romex labeled? If not, that precludes running them in conduit if you have a by the book inspector.

sdifox · Jun 7, 2025

Greenman said:
Are the actual wires in Romex labeled? If not, that precludes running them in conduit if you have a by the book inspector.

Jacket has marking no?

Sukhoi · Jun 7, 2025

sdifox said:
Jacket has marking no?

Yeah but the discussion is removing the jacket prior to running in conduit. It's fine to run in properly sized conduit if the jacket is not removed.

Greenman · Jun 7, 2025

sdifox said:
Jacket has marking no?

It does, but I don't recall if the wires inside the jacket are marked. If they aren't , and you take off the outer jacket, the inspector has no way to identify the wire and can reject it.

Question about conduit and wire for new circuit in unfinished room

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