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Wire Fill? #50292
03/29/05 08:52 PM
03/29/05 08:52 PM
N
NJ Wireman  Offline OP
Member
Joined: Aug 2004
Posts: 186
New Jersey (South Jersey)
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.

Work Gear for Electricians and the Trades
Re: Wire Fill? #50293
03/30/05 04:23 PM
03/30/05 04:23 PM
E
earlydean  Offline
Member
Joined: Dec 2003
Posts: 751
Griswold, CT, USA
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?


Earl
Re: Wire Fill? #50294
03/30/05 04:29 PM
03/30/05 04:29 PM
R
rad74ss  Offline
Member
Joined: Apr 2004
Posts: 156
Pryor, OK USA
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.

Re: Wire Fill? #50295
03/30/05 10:36 PM
03/30/05 10:36 PM
E
Electric Eagle  Offline
Member
Joined: Apr 2002
Posts: 914
Alpharetta, GA
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.

Re: Wire Fill? #50296
03/30/05 11:19 PM
03/30/05 11:19 PM
S
stamcon  Offline
Member
Joined: Mar 2001
Posts: 330
So San Francisco CA
Disregard this post..... [Linked Image]

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).]


Steve
Re: Wire Fill? #50297
03/30/05 11:25 PM
03/30/05 11:25 PM
P
PCBelarge  Offline
Member
Joined: Jun 2003
Posts: 681
Dobbs Ferry, NY, USA
10/2 NM installed in 1/2 conduit.... I think not! [Linked Image]

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

Pierre


Pierre Belarge
Re: Wire Fill? #50298
03/31/05 01:09 AM
03/31/05 01:09 AM
W
winnie  Offline
Member
Joined: Sep 2003
Posts: 649
boston, ma
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 [Linked Image]

-Jon

Re: Wire Fill? #50299
03/31/05 01:21 AM
03/31/05 01:21 AM
S
stamcon  Offline
Member
Joined: Mar 2001
Posts: 330
So San Francisco CA
Jon, my WAY bad. Thanks for the correction.

[Linked Image] steve [Linked Image]


Steve
Re: Wire Fill? #50300
03/31/05 01:59 AM
03/31/05 01:59 AM
G
gfretwell  Offline

Member
Joined: Jul 2004
Posts: 9,166
Estero,Fl,usa
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.


Greg Fretwell
Re: Wire Fill? #50301
03/31/05 10:12 PM
03/31/05 10:12 PM
H
highkvoltage  Offline
Member
Joined: Aug 2004
Posts: 34
Massillon, Ohio, USA
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)

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