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Wire Fill? #50292 03/29/05 09:52 PM
Joined: Aug 2004
Posts: 186
N
NJ Wireman Offline OP
Member
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 05:23 PM
Joined: Dec 2003
Posts: 751
E
earlydean Offline
Member
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 05:29 PM
Joined: Apr 2004
Posts: 156
R
rad74ss Offline
Member
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 11:36 PM
Joined: Apr 2002
Posts: 914
E
Electric Eagle Offline
Member
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 03/31/05 12:19 AM
Joined: Mar 2001
Posts: 333
S
stamcon Offline
Member
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 03/31/05 12:25 AM
Joined: Jun 2003
Posts: 681
P
PCBelarge Offline
Member
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 02:09 AM
Joined: Sep 2003
Posts: 649
W
winnie Offline
Member
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 02:21 AM
Joined: Mar 2001
Posts: 333
S
stamcon Offline
Member
Jon, my WAY bad. Thanks for the correction.

[Linked Image] steve [Linked Image]


Steve
Re: Wire Fill? #50300 03/31/05 02:59 AM
Joined: Jul 2004
Posts: 9,534
G
gfretwell Offline
Member
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 11:12 PM
Joined: Aug 2004
Posts: 34
H
highkvoltage Offline
Member
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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