# MC or AC90 Cable



## power (Feb 27, 2012)

I've a question for our American friends  :

Does all your armored cable have bonding conductors that are insulated in green? Or can you guys buy MC (or AC90 as we call it) with a bare ground? :001_huh:

All our armored cable has a bare bonding conductor. If we must install an isolated ground receptacle, we use three (3) wire MC. The red conductor is the "isolated" ground, and the bare conductor is the box's ground.


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## Year_Zero (Nov 3, 2013)

I'm pretty new at this but all the MC I've used has the grounding conductor insulated. I think the old school stuff with a bare aluminum bonding strip in it was called BX around here but I've never seen it in person.

What we would call "3 wire" MC in my area is black, red, white plus an insulated green ground wire. This is what we use for 208/240v or 3 way switching.

When we run IG circuits we use IG-MC (black wire, white wire, green wire bonded to box and green w/yellow stripe for the iso-ground).

I have been told (but have never seen it done) that it is legal to use the outer aluminum sheath of 2-wire MC as the bonding (grounding conductor) and the insulated green wire as a isolated ground in a run of 6 feet or less.

I don't know if this the standard across the US just what I know of personally.


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## Rochsolid (Aug 9, 2012)

power said:


> If we must install an isolated ground receptacle, we use three (3) wire MC. The red conductor is the "isolated" ground, and the bare conductor is the box's ground.


Or you could purchase the proper wire. We use 12/2 with insulated ground (4 conductors) for IG installations


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## cdnelectrician (Mar 14, 2008)

power said:


> I've a question for our American friends  :
> 
> Does all your armored cable have bonding conductors that are insulated in green? Or can you guys buy MC (or AC90 as we call it) with a bare ground? :001_huh:
> 
> All our armored cable has a bare bonding conductor. If we must install an isolated ground receptacle, we use three (3) wire MC. The red conductor is the "isolated" ground, and the bare conductor is the box's ground.


I don't think you would get a pass from ESA on that one...


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## power (Feb 27, 2012)

@Rocksolid - I think that would be a great idea, but our four (4) conductor MC doesn't have an insulated green neither, it's an insulated blue. And still with a bare ground.

@cdnelectrician - Are you referring to a pass failure because of using a red colored wire as a ground? Out here, we've done it for years and years......I think the inspectors don't think twice about it. Is this what your referring to?


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## Going_Commando (Oct 1, 2011)

I could blow some serious crap up if someone used a red or black wire as ground. :laughing:


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## wcord (Jan 23, 2011)

power said:


> @Rocksolid - I think that would be a great idea, but our four (4) conductor MC doesn't have an insulated green neither, it's an insulated blue. And still with a bare ground.
> 
> @cdnelectrician - Are you referring to a pass failure because of using a red colored wire as a ground? Out here, we've done it for years and years......I think the inspectors don't think twice about it. Is this what your referring to?


Using the red or blue conductor was allowed many years ago. Once insulated ground wire BX was available, using the red etc became against code.

BTW, there are 2 sizes of insulated green. 2c#12 AC90 with a #14 green is used for isolated ground receptacles. 2c#12 with a #12 green is required for patient care areas.


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## Southeast Power (Jan 18, 2009)

Year_Zero said:


> I'm pretty new at this but all the MC I've used has the grounding conductor insulated. I think the old school stuff with a bare aluminum bonding strip in it was called BX around here but I've never seen it in person.
> 
> What we would call "3 wire" MC in my area is black, red, white plus an insulated green ground wire. This is what we use for 208/240v or 3 way switching.
> 
> ...


And this is why we need state licensing...


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## oliquir (Jan 13, 2011)

you could use teck cable, gnd is bare but since there is an extra insulation between armor and wires it is isolated


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