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

Topic Options
Rate This Topic
#189139 - 09/21/09 02:48 PM 2011: AC, MC, ... Oh, I See!
renosteinke Offline
Cat Servant
Member
Registered: 01/22/05
Posts: 5305
Loc: Blue Collar Country
Alright, call me late to the party, but ...

A new ad by AFC Cable brought this issue to the forefront: Just what is the difference between AC and MC? Apart from what's printed on the UL lable, that is.

This matters, because there are a few places in the NEC where one is acceptable, while the other is not. For example, if you ever find one of those mythical AFCI devices, and wish to use it in place of an AFCI breaker, you can use AC, but not MC. Health care locations are another such quagmire.

We have had "health care MC" around for a decade now (MC painted green), and Southwire has been marketing their "Simpull" MC (with a bare wire outside the mylar wrap, rather than the usual green wire) for half that time.
Now, it seems, AFC has done away completely with the inner mylar wrapping.
It seems that the 'definitions' I have had in my mind for these two products have been obsolete for some time. MC, contrary to what I thought, need not have a mylar wrapper ... and that bare ground they're putting in some MC pretty much duplicates the bond wire in AC.

Maybe it's time to combine these two sections, consolidate the UL standards, and eliminate the code restrictions on MC?
Top
2017 / 2014 NEC & Related Books and Study Guides
#189148 - 09/21/09 08:57 PM Re: 2011: AC, MC, ... Oh, I See! [Re: renosteinke]
leland Offline
Member
Registered: 08/20/07
Posts: 856
Loc: Lowell area, Ma. USA
Years ago-Mcs' first arrival,it had thhn 105C rated. AC did not.This was why we could use MC in fire alarm systems but not AC. Now I'm not sure of the difference either.Just the jacket-AL or steel.

Top
#189150 - 09/21/09 09:32 PM Re: 2011: AC, MC, ... Oh, I See! [Re: leland]
Yoopersup Offline
Member
Registered: 03/04/03
Posts: 826
Loc: Michigan
AFC puts out a Great book on there cables, Most electricans & even some inspectors do not know the proper uses for AC , MC, Hospital Grade.
Yoopersup
Top
#189153 - 09/22/09 12:40 AM Re: 2011: AC, MC, ... Oh, I See! [Re: Yoopersup]
gfretwell Offline


Member
Registered: 07/20/04
Posts: 9066
Loc: Estero,Fl,usa
I suspect AC might just go the way of K&T. MC is overlapping it in virtually every regard. Guys like AFC are making MC in just about any configuration you could think of. It is becoming the most versatile wiring method out there.
_________________________
Greg Fretwell
Top
#192629 - 02/20/10 10:48 AM Re: 2011: AC, MC, ... Oh, I See! [Re: gfretwell]
harold endean Offline
Member
Registered: 02/16/02
Posts: 2248
Loc: Boonton, NJ
Greg,

I hated to use AC cable, I would only use MC once it came out. The old AC cable was useless if you had a lazy installer. They forgot to tighten up the connectors and you would lose your ground. I also saw where the outside case rusted away and the grounding was also lost.
Top
#192632 - 02/20/10 11:11 AM Re: 2011: AC, MC, ... Oh, I See! [Re: harold endean]
gfretwell Offline


Member
Registered: 07/20/04
Posts: 9066
Loc: Estero,Fl,usa
They are making the new MC cable that uses the armor, with an internal aluminum conductor, for the ground path. I am curious how well that will stand the test of time. You do not terminate that aluminum conductor in any way beyond the clamp on the armor and they depend on incidental contact to the armor inside the cable for the ground path. If this is not a gas tight connection it will oxidize, in my opinion. I am curious how well it will perform after 20 years in a real world environment, particularly if that real world was damp, maybe with a little salt air.
_________________________
Greg Fretwell
Top
#192647 - 02/20/10 11:00 PM Re: 2011: AC, MC, ... Oh, I See! [Re: gfretwell]
N844AA Offline
New Member
Registered: 02/02/10
Posts: 3
Loc: California
I seldom see AC cable these days.
Top

Featured:

2017 NEC and Related
2017 NEC
Now Available!

Shout Box

Recent Posts
Looking for older post
by sparkyinak
Today at 12:27 AM
License exam
by TRUE POWER
Yesterday at 11:33 PM
Members: Non-Members: Did you know?
by Admin
Yesterday at 02:34 PM
Safety at heights?
by HotLine1
01/21/17 08:51 PM
International Wire Colour Codes
by Texas_Ranger
01/21/17 03:29 PM

Who's Online
1 registered (sparkyinak), 108 Guests and 11 Spiders online.
Key: Admin, Global Mod, Mod
New in the Gallery:
Desk-mounted "power-board"
Top Posters
gfretwell 9066
Trumpy 8560
pauluk 7693
HotLine1 6833
sparky 5545
Member Spotlight
Member Since: 08/01/07
Posts: 62

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