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#53001 06/15/05 01:40 PM
Joined: Jul 2004
Posts: 9,745
Likes: 13
G
Member
Since we a talking about obscure wiring methods is anyone using NMC?
When I started looking at the wire manufacturers they shunt me off to UF.

My wild guess is that NMC is NM with a plastic wrapper instead of the paper so it would not wick up water but that is just a guess. I can honestly say I have never seen it and none of the supply houses I have visited stock it.


Greg Fretwell
#53002 06/15/05 05:13 PM
Joined: Aug 2003
Posts: 1,374
R
Moderator
I also have never seen it. I have never seen NM-S either.


Ryan Jackson,
Salt Lake City
#53003 06/16/05 12:35 PM
Joined: Feb 2005
Posts: 693
L
Member
I believe the "C" designation refers to corrosive environments.

[This message has been edited by Larry Fine (edited 06-16-2005).]


Larry Fine
Fine Electric Co.
fineelectricco.com
#53004 06/16/05 07:54 PM
Joined: Jun 2005
Posts: 4
N
Junior Member
The C refers to the temperature rating of the cable.

Frank


Frank
#53005 06/16/05 10:49 PM
Joined: Nov 2002
Posts: 793
Likes: 2
W
Member
Years ago back in college, homework done, had a few hours to kill poking around in the engineering library. Found a book on electrical wiring codes (don't remember which book, it even might have been from Europe) and thumbed thru it. One wiring method described was "Mineral Insulated Cable". If I recall correctly it consisted of a metal pipe and two (or more) conductors. Insulation was some sort of high temperature material, which didn't like moisture. You needed special connectors (compression?) and white and black insulating tubing to slip over the wires so you could wire things up in a box (wires were bare away from the mineral insulation in the pipe). Also sealent to keep moisture out. Maybe similar to what is done with heating coils on electric cooktops?

Is this something that is obsolete, or is likely found in nuclear power plants or other exotic environments? Maybe a steel mill?

#53006 06/17/05 12:08 AM
Joined: Jan 2005
Posts: 5,349
Likes: 1
Cat Servant
Member
wa2wise, please see the non-US forum for a discussion of "pyrotex."

#53007 06/17/05 01:48 AM
Joined: Jul 2004
Posts: 9,745
Likes: 13
G
Member
Bob teased the home inspectors with this the other day.
http://www.sesco-ge.com/pd_pyrotenax.htm


Greg Fretwell
#53008 06/17/05 05:48 PM
Joined: Nov 2002
Posts: 174
K
Member
NM Non-metallic sheathed cable, braid or plastic covered. For dry use, 60°C.

NM-B Non-metallic sheathed cable, plastic covered. For dry use, 90°C.

NMC Non-metallic sheathed cable, plastic or neoprene covered. Wet or dry use, 60°C, and corrosive applications.

According to NEMA, "Types NMC and NMS are not commercially available, but type UF-B can be substituted for NMC. Type NMS is a construction consisting of NM-B and data/communications cables."


[This message has been edited by kale (edited 06-17-2005).]

#53009 06/17/05 06:07 PM
Joined: Jan 2003
Posts: 4,391
I
Moderator
wa2ise regarding MI cable.

Quote
Is this something that is obsolete, or is likely found in nuclear power plants or other exotic environments? Maybe a steel mill?

Not obsolete in the least.

It is commonly installed as feeders for emergency circuits.

I saw a good video of it under test, it survived a couple of hours directly in a large (huge) flame all the while it was still conducting power just fine.

Here is a photo of MI in a Hospital.

[Linked Image from nachi.org]

And here is a close up of the connectors

[Linked Image from nachi.org]

This is single conductor MI that is why you see it in groups of four phases A, B, C, and N.

The brass plate is needed to comply with 300.20(B).


Bob Badger
Construction & Maintenance Electrician
Massachusetts
#53010 06/17/05 06:30 PM
Joined: Aug 2003
Posts: 1,374
R
Moderator
Great pics Bob! I'm going to have to save those for some presentations. [Linked Image]


Ryan Jackson,
Salt Lake City
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