The Electrical Contractor Network

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

Books, Tools and Test Equipment for Electrical and Construction Trades

Register Now!

Register Now!

We want your input!

Featured:
   

2017 NEC and Related
2017 NEC
Now Available!

   
Recent Posts
Industrail Control Panel bonding per 409.108
by sparkyinak
Yesterday at 03:17 PM
Calling all Non-US members!! (Non-US only)
by aussie240
12/07/16 02:39 AM
Photo Upload Tutorial
by DanK
12/06/16 11:35 PM
Sprinklered equipment 26-008
by bigpapa
12/02/16 04:24 PM
On Delay Relay with Auto Reset
by Potseal
12/01/16 09:59 AM
New in the Gallery:
12.5A through 0.75mm˛ flex (just out of curiosity)
Shout Box

Top Posters (30 Days)
gfretwell 13
HotLine1 9
Texas_Ranger 8
sparkyinak 8
Trumpy 6
Who's Online
0 registered (), 192 Guests and 6 Spiders online.
Key: Admin, Global Mod, Mod
Topic Options
Rate This Topic
#90572 - 11/30/04 08:58 AM NM in conduit
energy7 Offline
Member

Registered: 06/10/02
Posts: 58
Loc: Oxnard, CA, USA
A comment in the "horse barn" thread has stirred this question.
Can you run NM in conduit for any significant distance. My understanding of 336-6 (and now 334-15) is that conduit protection is used in short runs for specific hazards.
Because NM is a cable assembly and not just conductors, running it in conduit is "mixing wiring methods", and you're subject to overheating.

Top
2014 / 2011 NEC & Related Books and Study Guides
#90573 - 11/30/04 09:10 AM Re: NM in conduit
Roger Offline
Member

Registered: 05/18/02
Posts: 1779
Loc: N.C.
This has been cleared up in the 2005 NEC.

It is specifically allowed in the .22 sections of the conduit articles if the particular cable article doesn't prohibit it.

Roger

Top
#90574 - 11/30/04 09:39 AM Re: NM in conduit
gfretwell Offline

Member

Registered: 07/20/04
Posts: 9045
Loc: Estero,Fl,usa
I don't see how heating is considered an issue at all, code wise. You derate the same in 1/2" conduit as you do in 4" for the same conductor fill. A piece of Romex in "free air" EMT will certainly run cooler than it would buried in insulation in an attic.
_________________________
Greg Fretwell

Top
#90575 - 11/30/04 09:50 AM Re: NM in conduit
gfretwell Offline

Member

Registered: 07/20/04
Posts: 9045
Loc: Estero,Fl,usa
the .22 additions only point out rules that always existed. Basically you use the widest dimension of an oval cable as the diameter when computing fill. That is because when you get a twist in it the widest dimension becomes the diameter.
_________________________
Greg Fretwell

Top
#90576 - 11/30/04 08:07 PM Re: NM in conduit
John Steinke Offline
Member

Registered: 04/03/01
Posts: 509
Loc: Reno,Nv., USA
Romex is listed as a 60 degree assembly.
The THHN wire inside romex is listed as a 90 degree wire.

By putting romex in pipe, you are throwing away 30 degrees of de-rating, before you do anything else.

Also, the inside of conduit can sometimes be considered a wet location; romex is not allowed in wet locations.

Top



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