It depends. The old style MC cable armor is not listed for bonding but there is a new style MC that does use the armor for bonding. AFC calls theirs "MC-Quik", designated as type MCI-A. I assume there are other manufacturers by now. It can be identified by the large bare aluminum conductor right under the armor. This conductor is just for bonding the wraps of the armor and does not need to be terminated in the box.
Greg, I might have miss read the OP but I read his question was if the metal sheath of MC cable can be used for bonding. If that's true than the answer should show that if the sheath is the smooth variety or the corrugated variety the answer is yes. If it is of the interlocked variety like flexible metallic conduit (Greenfield) the answer would be no. Now they have come out with others inn recent years but I think my answer still stands. Now I presume that "Akmaster" is talking about the armor not the conductor inside the armor making it suitable as a grounding conductor.
George, the AFC product looks a lot like regular old spiral armor MC cable. There is a bonding conductor inside but it gets cut off flush with the armor. You use the proper listed MCI-A connector, just like you would with an AC connector. I suppose you could say the bonding is actually done with the internal conductor but you do not terminate it anywhere. The only connection is to the armor.
They print a notice on the neutral conductor so you can identify it after installation.
Hi, Thanks for the helpful responses. I am talking about the corrugated metal under the sheath of MC cable not AC or BX type. This is used in an industrial facility. I have not seen this type of MC cable with separate bonding conductor.I am not sure if it is interlocked (probably is)but we strip it back and terminate with an MC connector, all conductors pass through the connector...insulated and bare grounding wires. I was under the impression you could not use the metal clad armor of this cable for bonding. I have seen cases where they would strip away the outer sheath and attach a clamp to the metal clad armor and connect it to building steel. Sounds like a violation to me.
Akmaster: I'm a little confused at the moment. You said... " I am talking about the corrugated metal under the sheath of MC cable not AC or BX type. This is used in an industrial facility."
What 'sheath' are you refering to? Do you mean the type of MC cable that has an outer PVC jacket? That requires a connector that is specific to that cable, with the 'quick grip' fingers that bond the metalic sheath within that connector, but there is no 'bare ground' within that cable assembly.
I have a small piece here in the office, and one connector. The connector has no info, other than a 'B' and UL. Jacket is marked '12/3 SUPER....; just partial, 2 hots, 1 neutral & grn ground. Neutral is #10, all are THHN /THWN.
I guess this MCI-A is not that popular. The only time I ever saw it was at an inspector meeting where the AFC rep was pitching it to us. It was not PVC jacketed. It sounds like GW is talking about the regular old MC with a jacket and if it doesn't have the “armor is equipment grounding path component” printed on the white wire it is not MCI-A. I assume there is a green wire in there.
You do bond the armor but it is not your sole bonding path. You still terminate the green wire to the box and devices.
Hi, Yes I am referring to the PVC jacketed type MC cable. It is color coded..black, red and yellow are most common colors of outside jacket. it's NOT SO Cord or smooth jacketed cable. There is a bare conductor inside these cables sometimes one and sometimes three. Never have seen one with a aluminum bonding conductor that needs to be cut off where it exits the armor. These cables require mc connectors and have a circular spring inside that makes contact with the corrugated armor. This stuff is not cheap and is used mostly at refineries and oil and gas plants etc.
Akmaster: THe MC I described above is not a common item, I have seen it installed on only two (2) jobs over the last 10 years. Both jobs were the same EC, both installs were branch circuits (20 & 30 amp); the 20 amps were MWBCs. He used this type MC as it was encased within/under the slabs, instead of the 'old way' of raceways and THHN/THWN.
The outer jacket was all black as I remember; and the piece I have has NO internal bond conductor, as above.
You may have something specific to Alaska, or a specific industry!