what is the difference between AC and MC cable

[jimthies]

what is the difference between AC and MC cable?
When would AC not be allowed and MC allowed?

 

[George Stolz]

Re: what is the difference between AC and MC cable

You'll find AC cable in Article 320, MC cable is Article 330. Under uses permitted, you'll find MC cable is allowed in more locations, hence it's tougher stuff.

If I said more than that I'd be speculating.

 

[iwire]

Re: what is the difference between AC and MC cable

Originally posted by jimthies:
what is the difference between AC and MC cable?
When would AC not be allowed and MC allowed?

Your best bet is to read Articles 320 and 330 just as George suggested.

To say MC is tougher is not quite on the money it can be tougher or it can be weaker.

I can order MC with steel armor, light weight steel armor or aluminum armor.

The steel is very 'tough'

The aluminum is almost as easy to cut as NM.

MC is allowed in places of assembly AC is not but there are many more differences than just that.

 

[physis]

Re: what is the difference between AC and MC cable

Would one of those differences be the lack of a grounding conductor or is that size dependant or something else?

 

[iwire]

Re: what is the difference between AC and MC cable

Originally posted by physis:
Would one of those differences be the lack of a grounding conductor or is that size dependant or something else?

I do not know all the ins and outs of MC cable either.

The kind of MC I work with always has a grounding conductor and it looks like any AC cable on the outside.

There are also kinds of MC cable that have smooth tubular sheaths that are listed as the grounding means.

Standard AC cable does not have a grounding conductor no matter how big.

Then you get to Hospital grade AC this has the additional grounding conductor of MC and the armor is listed for grounding.

Many branch circuits in hospitals require redundant grounding, that is where the Hospital AC comes in it has two grounding means built in.

We use MC cable in sizes up to 4/0 /4 copper, this is perfect for a 225 amp 3 phase 4 wire feeder.

It is also the size of a fire hose (really looks like 1.5" flex) and heavy as you can imagine.

But with the right equipment and enough help it installs quick.

 

[physis]

Re: what is the difference between AC and MC cable

Sounds fun. I don't get to do much big stuff. I keep thinking of leaning away from residencial/ commercial towards commercial/industrial. It's a big change though.

 

[jtester]

Re: what is the difference between AC and MC cable

The basic difference between AC and MC is the internal green ground wire in MC cable and the fact that the sheath is not listed for grounding; and AC cable where there is no green ground wire, and the sheath is listed for grounding because of the little steel wire welded along the corrugations parallel to the wire.

Hospital greade AC cable has both the sheath listed for grounding AND a green ground wire.

Jim T

 

[iwire]

Re: what is the difference between AC and MC cable

Originally posted by jtester:
The basic difference between AC and MC is the internal green ground wire in MC cable and the fact that the sheath is not listed for grounding;

Jim that is not entirely accurate, there are MC cables with the sheath listed for grounding.

250.118 Types of Equipment Grounding Conductors.

The equipment grounding conductor run with or enclosing the circuit conductors shall be one or more or a combination of the following:

(11)Type MC cable where listed and identified for grounding in accordance with the following:

a.The combined metallic sheath and grounding conductor of interlocked metal tape?type MC cable

b.The metallic sheath or the combined metallic sheath and grounding conductors of the smooth or corrugated tube type MC cable

Bob

 

[goldstar]

Re: what is the difference between AC and MC cable

At one of our contractors' associations meetings we had a rep from AFC cable systems give a 2 hour CEU course on AC and MC cables. You can go to this website to get more info . www.afcweb.com/afcu