MC cable bonding in a outlet box

[Tonyrand]

We are installing Hospital Grade MC cable on a job, can the redundant ground conductor that is a copper wire be pigtailed and terminated with the aluminum bonding conductor under the same green screw. or does the code require two green screws in the box? I am being told by an inspector that wire-nutting and pig-tailing the two is a problem due to the dissimilar materials

 

[infinity]

Are you referring to MCap with a solid #10 AL conductor in contact with the metal jacket?

 

[joebell]

I think what you are using is either a product called HFC-MC cable with a green finish to it or you are using MC-Ap. The HFC-MC I was taught to wrap the aluminum trace back around the sheath, It helps to hold the anti short bushing in place, but I'm not sure if that is even necessary. The redunant ground is acheived through the sheath of the cable and the grounding conductor in the cable.

As for the MC-AP all you need to do is cut the trace wire and again the sheath is one ground and the green counductor in the cable is the other.

 

[raider1]

With healthcare facility grade AC cable or MC-AP cable you only need to cut off the aluminum bond strip. It is not necessary to connect it to the box. The pur[pose of the aluminum bond strip is to lower the impedance of the outer jacket which is used as the fault current path.

You need to be careful backwrapping the aluminum bond strip some AC connectors are not listed to be used if the bond strip is backwarpped.

Chris

 

[texie]

I'm with raider1 on this. I would add that you need to be careful that the connectors are specifically listed to be used with the cable you are using.

 

[kwired]

The only purpose of the bare aluminum conductor is to lower impedance of the sheath. If you uncoil the sheath it will be much longer than it is assembled meaning it will have a higher impedance. This "bonding" conductor just shorts across all the turns of the sheat and reduces overall impedance. It is not necessary to do anything at all with the bonding conductor. It's purpose ends at the point where the sheath is removed from the cable and the bonding conductor can be cut flush with the sheath if you desire. Listed grounding fittings are required, But I don't think you will find any listed MC or AC cable fittings that are not also listed for grounding.

 

[Tonyrand]

Installing Hospital Grade MC cable (green) The inspector said either wrap around the cable or bond it to the box separately. Do not bond it to the green bonding conductor terminated in the box as installer did.
If I understand everyone here , to solve the problem and pass inspection, all I have to do is "cut" the aluminum conductor it does not have to be terminated, correct?

Thanks everyone for the responses

 

[kwired]

Installing Hospital Grade MC cable (green) The inspector said either wrap around the cable or bond it to the box separately. Do not bond it to the green bonding conductor terminated in the box as installer did.
If I understand everyone here , to solve the problem and pass inspection, all I have to do is "cut" the aluminum conductor it does not have to be terminated, correct?

Thanks everyone for the responses

That is correct, your inspector needs to read up on this product.

Here is a manufacturer link that does tell us to cut the bare bonding wire.

http://www.southwire.com/documents/MCAP_BrochureNEW.pdf