ECN Forum Forums General Topics of the Trade General Discussion Area Romex short run/pipe

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.