ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals

Page 1 of 2 1 2 >
Topic Options
Rate This Topic
#50292 - 03/29/05 05:52 PM Wire Fill?
NJ Wireman Offline
Member
Registered: 08/26/04
Posts: 186
Loc: 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.
Top
Work Gear for Electricians and the Trades
#50293 - 03/30/05 01:23 PM Re: Wire Fill?
earlydean Offline
Member
Registered: 12/22/03
Posts: 751
Loc: 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
Top
#50294 - 03/30/05 01:29 PM Re: Wire Fill?
rad74ss Offline
Member
Registered: 04/19/04
Posts: 156
Loc: 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.
Top
#50295 - 03/30/05 07:36 PM Re: Wire Fill?
Electric Eagle Offline
Member
Registered: 04/20/02
Posts: 914
Loc: 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.
Top
#50296 - 03/30/05 08:19 PM Re: Wire Fill?
stamcon Offline
Member
Registered: 03/24/01
Posts: 329
Loc: So San Francisco CA
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).]
Top
#50297 - 03/30/05 08:25 PM Re: Wire Fill?
PCBelarge Offline
Member
Registered: 06/08/03
Posts: 681
Loc: Dobbs Ferry, NY, USA
10/2 NM installed in 1/2 conduit.... I think not!

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

Pierre
_________________________
Pierre Belarge
Top
#50298 - 03/30/05 10:09 PM Re: Wire Fill?
winnie Offline
Member
Registered: 09/15/03
Posts: 649
Loc: 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

-Jon
Top
#50299 - 03/30/05 10:21 PM Re: Wire Fill?
stamcon Offline
Member
Registered: 03/24/01
Posts: 329
Loc: So San Francisco CA
Jon, my WAY bad. Thanks for the correction.

steve
Top
#50300 - 03/30/05 10:59 PM Re: Wire Fill?
gfretwell Offline


Member
Registered: 07/20/04
Posts: 9039
Loc: 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
Top
#50301 - 03/31/05 07:12 PM Re: Wire Fill?
highkvoltage Offline
Member
Registered: 08/13/04
Posts: 34
Loc: 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)
Top
Page 1 of 2 1 2 >

Member Spotlight
Member Since: 08/22/05
Posts: 44
New in the Gallery:
SE cable question
Featured:

2017 NEC and Related
2017 NEC
Now Available!

Shout Box


Who's Online
0 registered (), 81 Guests and 7 Spiders online.
Key: Admin, Global Mod, Mod
 
New in the Gallery:
SE cable question
 
Top Posters (30 Days)
Admin 47
HotLine1 43
gfretwell 19
Ruben Rocha 12
Trumpy 9
 
Newest Members
KrmtFrg, Stack, Scotto, Freecrowder, clee512

ECN Electrical Forums - sponsored by Electrical Contractor Network - Electrical and Code Related Discussion for Electrical Contractors, Electricians, Inspectors, Instructors, Engineers and other related Professionals