MC cable versus AC

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If price is the same, what if any advantage or disadvantage is there to using either AC or Mc cable.
Obviously there is a small amount of extra labor with terminating the grounding conductor in MC cable.But other than that ? ?
 

david

Senior Member
Location
Pennsylvania
In the past AC cable always had more grease on the Armor and you had to be very careful with what finish surfaces you touched while working with AC in a finished building.

AC cable was always harder to remove the armor than MC cable.

The anti shorts where harder to put on the with AC

On the other hand we used a lot of AC on lighting circuits in the past
 

tom baker

First Chief Moderator
Staff member
AC is an older product, paper wrap, requires red heads and support every 4.5 ft. But it does not have an EGC to make up, made by AFC, the jacket is the EGC
MC is a new product, mylar wrap, no redheads, support every 6 ft, but does have the EGC conductor to make up, its make by Southwire

Southwire was losing a lot of market share to AFC in heathcare apps where you could run AC with an EGC. Can't do the same with traditional MC

So Southwire came up with MC-AP, which is mylar wrap, and the jacket is the EGC. So now on every installation you don't have to make up the EGC, so you save 30% on labor. And Southwire has an MC-AP health care version with an EGC so now they can compete against AFC.

http://www.southwire.com/products/MCAPTypeMCAllPurpose.htm

the contractors that are using MC-AP love it.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
If price is the same, what if any advantage or disadvantage is there to using either AC or Mc cable.
Obviously there is a small amount of extra labor with terminating the grounding conductor in MC cable.But other than that ? ?

I think that it's more than a small savings not having to terminate an EGC at every termination. For all two wire cables that 33% less terminations every time you cut the cable and terminate it.
 

ceb58

Senior Member
Location
Raeford, NC
AC is an older product, paper wrap, requires red heads and support every 4.5 ft. But it does not have an EGC to make up, made by AFC, the jacket is the EGC
MC is a new product, mylar wrap, no redheads, support every 6 ft, but does have the EGC conductor to make up, its make by Southwire

Southwire was losing a lot of market share to AFC in heathcare apps where you could run AC with an EGC. Can't do the same with traditional MC

So Southwire came up with MC-AP, which is mylar wrap, and the jacket is the EGC. So now on every installation you don't have to make up the EGC, so you save 30% on labor. And Southwire has an MC-AP health care version with an EGC so now they can compete against AFC.

http://www.southwire.com/products/MCAPTypeMCAllPurpose.htm

the contractors that are using MC-AP love it.
The MC-AP has an alum. wire woven into the sheath that must be bent back and trimmed before inserting in the connector. If you have a lot to run with a lot of terminations it is worth it. But at a difference of $200.00 per 1000 ft some times it is not a money saver verse regular MC.
 

conmgt

Senior Member
Location
2 Phase Philly
I've always preferred AC to MC.
One less wire to terminate, less copper used (its a waste of resources), one less conductor in the cable to fight while making bends, and when you get into heavier gauges,
AC is lighter. For years now I've been able to find AC with a AL jacket.
 

Wire_nutz

Member
The MC metal outer cable sheath is solid not spiral like AC/BX cable. The spiral cable jacket on AC/BX is approximately 2 or 3 times the cable length. When outer metal cable sheaths are used as the EGC path the solid metal jacket is shorter and has less resistance than the spiral jacket.

Example: 1 ft. of the spiral AC/BX jacket stretched would equal 3 ft. and 100 ft. of AC/BX would equal approximately 300 ft.

The solid cable metal jacket has a shorter return ground path. Copper wire as an EGC has less resistance than the steel outer jackets and using a cable with an EGC does have some benefit.
 

conmgt

Senior Member
Location
2 Phase Philly
I'm not sure what you mean by MC cable being solid and not spiral. Or you're thinking of a different cable. This is what I mean by MC and it has a spiral like AC. And I'm not convinced the extra length and its steel composition makes a difference.
 

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kwired

Electron manager
Location
NE Nebraska
320.2 Definition.
Armored Cable, Type AC. A fabricated assembly of insulated conductors in a flexible interlocked metallic armor. See 320.100.

330.2 Definition.

Metal Clad Cable, Type MC. A factory assembly of one or more insulated circuit conductors with or without optical fiber members enclosed in an armor of interlocking metal tape, or a smooth or corrugated metallic sheath.

I haven't seen much AC cable in recent years, AFAIK you can get it with steel or aluminum armor though aluminum is most common.

I have seen MC in steel and aluminum, smooth or corrugated, and spiral armor.

Biggest difference between the two is that AC has paper fillers and MC has mylar fillers under the sheath. AC also has the bonding conductor just under the sheath, but products like MC-AP have narrowed the gap between them, as it also has a bonding conductor.



 

mark32

Senior Member
Location
Currently in NJ
An electrician recently told me the following. He had placed a roll of mc on his basement's concrete floor. A few months pass and he picks it up but notices all of the armor that had been touching the concrete had vanished, eaten away by the concrete. Upon hearing this I would choose ac over mc whenever you'd have to strap it to such a surface. Anyone have similar experiences?
 

david

Senior Member
Location
Pennsylvania
An electrician recently told me the following. He had placed a roll of mc on his basement's concrete floor. A few months pass and he picks it up but notices all of the armor that had been touching the concrete had vanished, eaten away by the concrete. Upon hearing this I would choose ac over mc whenever you'd have to strap it to such a surface. Anyone have similar experiences?

I would wonder more about Alum verses steal rather than AC verses MC on concrete. I never seen this seen a lot of MC fastened to concrete above suspended ceilings in hospitals. Also I would be suspicious that some outside chemical like bleach or something else was involve. Was there any excessive water on the floor, what did he wash the basement floor with ?
 

kwired

Electron manager
Location
NE Nebraska
An electrician recently told me the following. He had placed a roll of mc on his basement's concrete floor. A few months pass and he picks it up but notices all of the armor that had been touching the concrete had vanished, eaten away by the concrete. Upon hearing this I would choose ac over mc whenever you'd have to strap it to such a surface. Anyone have similar experiences?
The thing here is that it was aluminum armor. Same armor may be on AC or MC cable. There were likely other contributing factors to the corrosion of that armor. Anything below grade will have higher risk of some moisture and add other agents and you may accelerate the process.

I have had pieces of MC cable laying on concrete in the shop for months and no noticeable deterioration
 
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