12/2 MC w/ a solid aluminum ground?

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Torok005

Member
Location
Bath MI, USA
I have recently reinstalled some salvaged 50 feet of 12/2 MC. I installed my recessed can fixtures and began installing 6' pieces of said MC to their respective 4 squares. Upon stripping the MC I found that the hot and neutral are 12 gauge stranded copper and the bare ground appears and feels like a solid aluminum. Is this a common type of MC or something used for a specific application or am I just plain wrong and it's a tinned piece of copper? Any input would be appreciated. Thanks in advance.
 

kwired

Electron manager
Location
NE Nebraska
I agree. White , Black and a bare aluminum wire is generally ac cable. If the cable had a green #12 also then I would say MC.

THe bare wire is not an egc per se but it helps the AC cable so it can be used as a ground
The MC-AP does not need to have a green conductor within, that is one of their marketing points is the time saved by not making up all the grounding conductors in boxes - the sheath with the aluminium bonding strip is the equipment grounding conductor.

This was typical for AC cable for years, why it took so long for someone to come up with an MC cable using a similar method of using the sheath for a ground is beyond me.

The type required for use in health care facilities is same thing with a green conductor.
 

ceb58

Senior Member
Location
Raeford, NC
The MC-AP does not need to have a green conductor within, that is one of their marketing points is the time saved by not making up all the grounding conductors in boxes - the sheath with the aluminium bonding strip is the equipment grounding conductor.

This was typical for AC cable for years, why it took so long for someone to come up with an MC cable using a similar method of using the sheath for a ground is beyond me.

The type required for use in health care facilities is same thing with a green conductor.
Very much agree. The only thing now is the OP must use an approved connector for the MC-AP
 

chris kennedy

Senior Member
Location
Miami Fla.
Occupation
60 yr old tool twisting electrician
He said it was MC. :D
And as a first time poster here I'm sure the OP used the correct term.;)

Very much agree. The only thing now is the OP must use an approved connector for the MC-AP
I had the long list of all the listed connectors that was posted here before but lost it a while back. Anyone remember that and have the link?
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
And as a first time poster here I'm sure the OP used the correct term.;)




I had the long list of all the listed connectors that was posted here before but lost it a while back. Anyone remember that and have the link?

Yes, it could go either way. :happyyes:
 

kwired

Electron manager
Location
NE Nebraska
I had the long list of all the listed connectors that was posted here before but lost it a while back. Anyone remember that and have the link?
Is possible the list of not listed connectors is shorter, not certain I have seen one that is not listed, and I would guess that there is even less chance of it being listed for AC/MC cable but not be listed for grounding.
 

Torok005

Member
Location
Bath MI, USA
Thanks for the input fellas . . . . my question inadvertently cleared up my confusion on AC/MC as well. I connected the EGC to the ground in the can light via scotch lock and a dab of antiox. compound. A little flaky but I figured it was better than nothing. Thanks again
 

kwired

Electron manager
Location
NE Nebraska
Thanks for the input fellas . . . . my question inadvertently cleared up my confusion on AC/MC as well. I connected the EGC to the ground in the can light via scotch lock and a dab of antiox. compound. A little flaky but I figured it was better than nothing. Thanks again
The aluminum wire within the cable is not an equipment grounding conductor, it is a bonding strip, its purpose is to short the turns of the spiral armor to make less impedance in that armor if it should be called upon to carry current. Look carefully at construction of the cable and you will notice all the conductors in the cable are inside a plastic wrap but this bare aluminum is outside that plastic and in intimate contact with the armor. It does not need terminated and in fact can be cut short when stripping the sheath.

The equipment grounding conductor of the cable is the combination of the sheath and this bonding strip together. If the cable does not have the bonding strip, it will have a green conductor within, which used to be the typical design of MC cable.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
Look carefully at construction of the cable and you will notice all the conductors in the cable are inside a plastic wrap but this bare aluminum is outside that plastic and in intimate contact with the armor. It does not need terminated and in fact can be cut short when stripping the sheath.
Yup, right there in post #2. ;)
 

horsegoer

Senior Member
Location
NJ
The MC-AP does not need to have a green conductor within, that is one of their marketing points is the time saved by not making up all the grounding conductors in boxes - the sheath with the aluminium bonding strip is the equipment grounding conductor.

This was typical for AC cable for years, why it took so long for someone to come up with an MC cable using a similar method of using the sheath for a ground is beyond me.

The type required for use in health care facilities is same thing with a green conductor.
So basically MC-AP and AC are the same?
 
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