When adding a circuit with NM in a finished home that is run through the attic then dropping the from the eve area straight down to the panel with an LB. Can this be run in pipe for mechanical protection? It would seem dumb to put in a WP box and have to splice it with THHN just for the short foot or two of EMT.

Not and meet the requirements of the Code. A provision was added to permit the stovepipe installation for surface mount panelboards but not when they are flush mount. How do you clamp the cable where it enters the panelboard?

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Charlie Eldridge, Indianapolis, Utility Power Guy

[This message has been edited by CharlieE (edited 10-16-2004).]

This has always driven me nuts. Seems to be a stupid rule. What hazards could there be? Heat....then derate? How would you clamp THHN? What is romex but glorified THHN anyways. Once you strip the outer sheating you are left with THHN no.....except you have a bare ground.

Aldav53,

Is this a generic question, or do you have a specific installation in mind?

• Is the panel flush or surface?
• Is the location interior or exterior?
• Is mechanical protection actually needed, i.e., how are the other branch circuits entering the panel?

You wouldn't need to strap the THHN because it only runs from the panel, through the emt, then ends at the junction box, so just strap the emt.

Maybe I'm not understanding the question. If the question is can you run NM in conduit, the answer is yes you can. It seems the other obstacle is securing the cable within 12" of where it enters the panel. I really don't think this is an issue if it is stapled just before it enters the conduit. the purpose of securing it 12" from the panel is to prevent it from being pulled out, I think the conduit will serve that function. If you had an inspector wanting a connection at the panel, you could use several diferent options inside the panel to keep it from pulling out.

They do make a romex to EMT connector. They look cheesy though. That would be considered support, as long as the conduit is supported.

Normally, I would leave an extra length, enough to make it into and be terminated in the panel. Bring it into a box with a few other romex, strip them all, ground them all there, and pull my extra long conductors into the panel. I have to do that for a lot of panels, as here below 8', romex is considered subject to physical damage. (Unlike a lot of other places in the country.)

The biggest problem I see with conduit chases between the attic directly into the top of the panel, is that condensation forms inside the conduit at the point between the unheated attic, and the heated interior of the building. Of course the water drips directly on top of the breakers, and runs down the back through the bussing. I've seen several completely destroyed panels caused by this. Depending on the temperature difference, the condensation can form so fast that it almost runs in a steady stream. Duxseal helps very little.

Can you just run the EMT a few inches short, into a ridgid coupling with an NM clamp threaded into the coupling on the inside of the panel to clamp it? Just an idea

Jim

To clear up confusion:
It is an outdoor surface mount panel (used mostly in AZ) the pipe will come out of the top of the panel and LB into the attic (through the soffit). So there is no need for staples. You can barely get into the attic to staple anyway.
From there the circuit runs over to and down a finised wall to a box.

As far as condensation, all the circuits are run down the wall and into the back of the panel. Thats how there all done in AZ. So if condensation were a problem, then all the houses here are wrong.

I agree with Electric eagle. The code section he refered to, allows you to use conduit to protect the wire. It doesn't say you have to break the conduit every 4 1/2 feet to staple the wire or break the conduit to staple the wire at the panel. I use the fitting that is both romex connector and EMT connector on the attic side and terminate the EMT at the panel as usual. I have never been called on it and have not lost a bit of sleep worrying about it either.

I think the key is 334.10(A)(1). Exterior conduit is a wet location.

Well, you are in "arid" Arizona. . .

Are you saying it never rains in Arizona so the outside of the home is not a wet location?

I believe the 2005 NEC will allow romex in conduit in the situation that aldav53 describes.

All conduit run out of doors is by definition (see Chapter 100) a wet location. Any conductors run in said conduit must be of the "W" type. NM is not, UF is. You could run UF indoors as well as outdoors, or do as you first thought, and switch wiring methods to THWN (not THHN) for the outdoor portion.

If the bottom end is open, it would drain any condensate that may form. (there are fittings designed for this purpose, or a small weep hole could be drilled in the bottom of the LB, in either case the entry into the panel would have to be sealed with duct-seal). It would be a simple matter to keep the conduit run from collecting any rainwater by the use of a gasket on the LB, and the use of raintight fittings, or by the use of PVC.

I use comp fittings with emt, so the NM is raintite. It enters a raintite outdoor panel. I put duct seal around the connector where it enters the panel and where it enters the soffit as an extra measure.

Aldav53, If the EMT is on the outside wall, NM isn't allowed in the location. The only modifier will be if the location is "protected". One might argue that an eave overhang of some distance is sufficient to protect the raceway of such and such length from the weather.

G.J., 334.10(A)(1) is unchanged in 2005. NM must still be installed in "normally dry locations."

In the attic - NM on one side of a 1900 (4" junction box), other side FMC (Greenfield), transition to EMT above the soffit on the exterior wall...

Hey, if I could fit a few more adapters in ther I would...

I think you could do it under 312-5(C) EX. The only thing is the pipe can't penetrate a structural ceiling, but this is a soffet. Would this be the same thing?

... This has been a note of contention I'd addressed on this forum once before.I had asked about it because there comes that time,when running a circuit in an unfinished basement,where you come down the wall with Romex,and you want it to be safe and look half-way decent,you sleeve it in pipe.You use a "from-to"... and I was told that that was wrong to do,...mainly because Romex is not rated for wet/damp locations...I must admit,..I still continue to do this,as I believe that if it's in conduit,..it's not exposed to the dampness/moisture,..etc. the same thing goes for running short lengths of Romex thru Liquid-Tite,outside,..as for an A/C unit..the wire is totally protected,grounded,bonded,and goes from the disconnect thru the Liquid-Tite,to the unit,and is protected from the elements therein,...why the problem??? Please clarify
Russ

I don't think that anyone here would argue if we use a small piece of pipe to protect a piece of RX. However the big question is, When is the pipe too long? A 4' piece is OK? Then how about a 10' lentgh? Maybe 20 or 30 feet? When do we stop. I saw a job where someone ran 60-90 feet of PVC with a 12-3 RX inside of the pipe. Is that too much? What is the code section? Now if it goes underground, you can argue the RX in a wet location like ElectricAl stated. However how much pipe is too much? Maybe you could ask the AHJ?

Harold

I agree Russ. How can moisture get to it if you use compression fitting.

Good point Harold, I just can't see where the problem is with running NM in pipe if it is weatherproof.

I'm with you Attic Rat on this, as I can not even get THWN,it is not even stocked at our several supply houses! I use THHN in conduit outside all the time! (Listed for damp location.) Maybe something unenforced here? Not that I'm looking for it to be, I like stocking one type of wire.

Wait, I just checked, its all dual rated............. THHN/THWN/MTW, just says THHN in larger lettering. Duh.... Just when you thought you could break some rules.

[This message has been edited by e57 (edited 10-19-2004).]

Oh, most RT fitting only become RT as they cross into Canada. There is something I get away with!