Transition from conduit to NM?

[MushCreek]

I'm going to be wiring my barn soon. I'm going to run conduit in the working area, since the walls aren't finished (and might not ever be). The question arises in transitioning from the conduit in the lower areas to NM once I'm higher up. I seem to recall you can have exposed NM above a certain height? I can't see running conduit all the way up to and across the ceiling for lights.

Can I just pull NM through the 3/4" conduit? Or should I run THHN to a junction box near the ceiling, and then NM? The wire going to the ceiling will only be for lighting, so we're talking 14 gauge.

 

[TheEquineFencer]

I'm going to be wiring my barn soon. I'm going to run conduit in the working area, since the walls aren't finished (and might not ever be). The question arises in transitioning from the conduit in the lower areas to NM once I'm higher up. I seem to recall you can have exposed NM above a certain height? I can't see running conduit all the way up to and across the ceiling for lights.

Can I just pull NM through the 3/4" conduit? Or should I run THHN to a junction box near the ceiling, and then NM? The wire going to the ceiling will only be for lighting, so we're talking 14 gauge.

If I were doing what you're planning on, I'd run THHN to a metal or PVC box depending on what type of conduit you're running and branch out from that box.

 

[sberry]

Just do it, why add extra connections if you don't need to.

 

[MushCreek]

It needs to be to code, both for inspections, and for my own peace of mind.

I guess it makes sense to run conduit to a box at the ceiling, then NM out to the various lights.

 

[sberry]

If it is for protection it is code and making it more busy isn't going to help. You probably need or want a box anyway so its an either way deal but there isn't much real reason to change wiring methods. Simply put a chunk of pipe on it where it can get banged around, that is the intent of it all.
Ok, I see you are going to pipe other stuff then I guess not a big deal as one will already have the materials.

 

[TheEquineFencer]

If it is for protection it is code and making it more busy isn't going to help. Second,,, mr Fencer is a swell guy but you are now responding to the first amateur post what he would do.
You probably need or want a box anyway so its an either way deal but there isn't much real reason to change wiring methods. Simply put a chunk of pipe on it where it can get banged around, that is the intent of it all.
Ok, I see you are going to pipe other stuff then I guess not a big deal as one will already have the materials.

WTF? I must have missed something...I thought he was running conduit down low with THHN...and wanted to run something like Romex up above open...

 

[sberry]

My bad. Sorry

 

[justsam]

The intent is to protect the wiring from possible harm.

Based on reading different inputs regarding this on this forum, it seems to be more of a jurisdictional call, as to what provides protection.

One of my past garages had thin wall conduit up to the plate line, the rest was open NM. There were no transition boxes, just NM in conduit.

You can also just enclose the wiring in that stud bay, creating a wire chase in effect. This could be plywood such that it could be removed in the future.

 

[wyliesdiesels]

I would use conduit throughout with THHN. Why introduce a failure point?

 

[MushCreek]

I'd rather not have to run conduit all over the ceiling- needless expense and cost. I like the idea of enclosing one stud bay with plywood. I'll have light switches- probably 3 or 4 right by the man door. One for external lights, and the others for 2 or 3 overhead light zones. I can't see lighting up the whole place if I'm working in one corner, or just need enough light to walk in. I'll run conduit horizontally from the breaker box to the switch box, then NM (behind a plywood panel) and then just continue the NM above the fire stop. The switch box will serve as the junction box. Anyone know off-hand how high above the floor unprotected NM has to be? When I wired my commercial shop about 15 years ago, I had to go up 8' with the conduit. I have fire blocking at 8'.

 

[iminocca]

In this area you can use Romex above 7'...you will need to make the transition in a box, you can't run Romex in conduit, legally.

 

[alfredeneuman]

In this area you can use Romex above 7'...you will need to make the transition in a box, you can't run Romex in conduit, legally.

I live and work in Orange County and you can run NM in conduit here.
There's no National Code prohibition against it.

 

[Cougar]

For outlets in the basement we ran conduit from the box up the wall to the floor joists. Ran NM in the conduit and open on the joists.

 

[Charles (in GA)]

For simple runs down the wall, install the box and conduit and drop the NM down it. No sense having splices you don't need and boxes you don't need. Just be mindful of the fill requirements for conduit.

If you want it to look nice and compliant there are EMT to NM clamps you can get, I know in ½ EMT and probably 3/4 also.

 

[MushCreek]

We're NEC 2008 here. I have a copy, but not sure where to look for it.

 

[txvwnut]

Why not use MC cable?
I knew it would be some time before I finished the inside of my garage so I ran MC throughout the whole building.

 

[MushCreek]

I'll look into MC; that would work well too. I have a few hundred feet of 14/2 and 14/3 NM left over from building the house, though. All of the outlets will be 12 ga.

 

[Charles (in GA)]

Why not use MC cable?
I knew it would be some time before I finished the inside of my garage so I ran MC throughout the whole building.

NEC treats type MC cable about the same as NM, it cannot be exposed where subject to damage.

330.12 Uses Not Permitted. Type MC cable shall not beused under either of the following conditions:
(1) Where subject to physical damage
(2) Where exposed to any of the destructive corrosive conditions in (a) or (b), unless the metallic sheath or armor is resistant to the conditions or is protected by material resistant to the conditions:
a. Direct buried in the earth or embedded in concrete unless identified for direct burial
b. Exposed to cinder fills, strong chlorides, caustic alkalis, or vapors of chlorine or of hydrochloric acids

 

[txvwnut]

NEC treats type MC cable about the same as NM, it cannot be exposed where subject to damage.

Good to know. Mine is run through the studs and up high for the lighting where it should be free from damage.