MC Feeder Cable Grounding conductor NEC 330

[chenkeljr]

Why do the MC cables used for large feeders contain bare grounding conductors, while the MC cables used for branch wiring have insulated grounding conductors?

I have reviewed NEC article 330 and found both constructions to be incompliance as they both insulate the ground conductor from the metal jacket. A client is requesting that the MC used on there projects for branch circuits have bare ground condctors. Thank you for your intrest.

 

[infinity]

Why would they request bare EGC's in a cable? Are you sure they don't mean MC-ap?

http://www.southwire.com/commercial/MCAPandHCFMCAP.htm

 

[chenkeljr]

No they want the ground to be isolated from the metal sheath. What is the advantages of a bare ground as oposed to a insulated ground in this type of assembly?

 

[infinity]

Sorry your OP said that they wanted a "bare ground".

As far as the NEC is concerned there is no difference since both will provide the required ground fault return path. IMO it doesn't really matter but the guy writing the spec obviously has something in mind.

 

[chenkeljr]

Yes wish his thoughts were shared instead of enforced. Hope someone can shine lite onto this issue. Thank you for your input. I feel that the insulated is a better way to go.

 

[don_resqcapt19]

No they want the ground to be isolated from the metal sheath. What is the advantages of a bare ground as oposed to a insulated ground in this type of assembly?

It can never be electrically isolated from the metal sheath. The metal sheath must be connected in some way to the EGC for the circuit.

 

[chenkeljr]

It will be connected to ground through the panel connection and box termination (metal box) just as any raceway. By isolated I mean in the construction of the cable. The cable has a non conductive protection between the wire and metal sheath. The bare ground in MC is full size not as in AC which is a reduced size for bonding only.