What size EMT, & PVC would be used if you were going to run on 30 amp 220 volt circuit. the run would be 10/2 romex pushed through this. I have been told that it requires 3/4" but every thing i have ever been tought tells me 1/2 would be fine. It is 2 conductors and a ground all solid 10awg copper. These hit a weather proof box befor going to pipe, it it required to strip down the romex from its outer jacket pprior to being fished.

Why would any sane electrician strip down a length of NM cable, instead of simply pulling the individual conductors?

To address your question: Chapter 9, Table 1 of the NEC, note 9 requires us to consider the cable as a single circular conductor with a diameter equal to the largest dimension of the cable. 53% fill.

What is the largest dimension of 10/2 Romex? using Table 4 for PVC, I see, for the 53% column, a maximum area of .151 sq. in. for 1/2 inch and .269 sq. in. for 3/4 inch conduit.
Doing the math, for 1/2 inch PVC conduit the maximum size would be .438 inches, and for 3/4 inch PVC the maximum size would be .585 inch.
I do believe to sleeve 10/2 we would need 1 inch PVC to meet code. Has anyone measured 10/2 Romex lately?

Save yourself much pain and foul language and change over to THHN in a 1/2". Running romex through EMT is like driving a tractor trailer in a parking garage, not worth the trouble.

Skip the formulas and go to annex C for ENT. Use THHN and it says 4 #10 conductors in 1/2", so 10/2 is OK.

Disregard this post.....

Essex Electric Company(cable manufacturer)
lists their 10/2 w/grnd as having the approximate dimensions of .22"x.49". Per Chapter 9, 1" EMT @40% fill is only good for .346", so 1¼" EMT would be needed. For RNC sch40, 1" is .333", so 1¼" RNC would also be needed. ½" EMT @ 40% fill is good for .122". Essex lists their 14/2 w/grnd as having the dimensions of .17"x.37", so even the 14/2 would need to be in 1¼".


steve

[This message has been edited by stamcon (edited 03-31-2005).]

10/2 NM installed in 1/2 conduit.... I think not!

Read the last sentence of Note (9) in Chapter 9.

Pierre

Stamcon,

Don't confuse diameter with area. The 10/2 has a cross section of 0.49x0.22, and thus an area of about 0.085 _square inches_. However code requires us to treat it as a circular object with a diameter of 0.49", or a 'code calculated area' of 0.189 square inches.

For a _single_ conductor or cable, you are allowed to go to 53% fill, so 3/4 EMT would be sufficient for this particular 10/2.

Note that if this is conduit in a wet location, you need wet rated conductors. NM-B is _not_ rated for wet location use. Also pulling individual THHN/THWN conductors is probably much easier

-Jon

Jon, my WAY bad. Thanks for the correction.

steve

Then I do this type of thing I cheat. Find a single conductor about the same diameter as the flat side of the cable and use the table for that conductor.

When you stated that you would need a weatherproof cover I'm thinking this would be located outside in which would be concidered a damp of wet location. Romex is not listed for these locations 334.12(B)(4)

Please brows this, and ponder what is a hand here: http://www.essexep.com/electrical/products/building/pdfs/Type%20NM-B%20Color%20Coded%20(NM%20Sheathed%20Cable.pdf

THHN conductors in paper and PVC sheath. Remove this paper and PVC sheath, and you have THHN conductors and a bare ground, right? Why don't they just use the dual rated THHN/THWN stuff they also make?

[This message has been edited by e57 (edited 04-01-2005).]

It's probably the paper that makes this dry only. That and NFPA

e57 ---

If I read the data sheet right, you can get NM with no paper. It is still only rated dry.

Then I guess we are stuck with what NFPA tells us. Proposals are still open for the 2008.

George-
"Why don't they just use the dual rated THHN/THWN stuff they also make?" It would make this situation much easier if they did.