ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat Box
Recent Posts
Where is Everyone?
by gfretwell - 04/09/21 01:08 AM
HI gang, long time since I was here...
by gfretwell - 04/09/21 01:02 AM
Lock-down Thread
by gfretwell - 04/06/21 09:30 PM
New in the Gallery:
Facebook follies, bad wiring
FPE in Germany pt.2
Who's Online Now
0 registered members (), 16 guests, and 18 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
2011: AC, MC, ... Oh, I See! #189139 09/21/09 05:48 PM
Joined: Jan 2005
Posts: 5,316
renosteinke Offline OP
Cat Servant
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?

2017 / 2014 NEC & Related Books and Study Guides
Re: 2011: AC, MC, ... Oh, I See! [Re: renosteinke] #189148 09/21/09 11:57 PM
Joined: Aug 2007
Posts: 853
leland Offline
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.

Re: 2011: AC, MC, ... Oh, I See! [Re: leland] #189150 09/22/09 12:32 AM
Joined: Mar 2003
Posts: 849
Yoopersup Offline
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.

Re: 2011: AC, MC, ... Oh, I See! [Re: Yoopersup] #189153 09/22/09 03:40 AM
Joined: Jul 2004
Posts: 9,575
gfretwell Offline
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
Re: 2011: AC, MC, ... Oh, I See! [Re: gfretwell] #192629 02/20/10 02:48 PM
Joined: Feb 2002
Posts: 2,233
harold endean Offline

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.

Re: 2011: AC, MC, ... Oh, I See! [Re: harold endean] #192632 02/20/10 03:11 PM
Joined: Jul 2004
Posts: 9,575
gfretwell Offline
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
Re: 2011: AC, MC, ... Oh, I See! [Re: gfretwell] #192647 02/21/10 03:00 AM
Joined: Feb 2010
Posts: 3
N844AA Offline
New Member
I seldom see AC cable these days.


2020 National Electrical Code
2020 National Electrical
Code (NEC)

* * * * * * *

2020 Master Electrician Exam Preparation Combos
2020 NEC Electrician
Exam Prep Combos:
Master / Journeyman


Member Spotlight
Kansas City, KS
Posts: 30
Joined: January 2013
Show All Member Profiles 
Top Posters(30 Days)
BigB 1
Popular Topics(Views)
277,518 Are you busy
211,224 Re: Forum
198,250 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.3