Grounding two 3-phase supplies in a cabinet

[nimabakhshi]

Hello everyone,

We are using two existing plugs (three-phase 120/208 V AC) to power a control cabinet (metallic enclosure). Since each one of the plugs on their own does not have the required amperage, we are using two plugs at the same time. One supply is 40 AMP to power motors, the other one is 30 AMP to power heaters, DC power supplies, etc (only 10 AMP used).

My question is what is the best practice or code requirement for bonding and grounding of this system. Should we have a central ground bar in the cabinet and bond both grounding conductors of the incoming three-phase supplies to this bar? Then bond enclosure, equipment earth and DC negative to the ground bar?

Or should only bond the grounding conductors of each power line with the earth of the equipment it is feeding? (in this case is the enclosure bonded to each of those separate ground bars?)

Would appreciate your expertise!

 

[LarryFine]

I suggest a single common grounding bar.

 

[nimabakhshi]

two existing plugs (three-phase 120/208 V AC) to power a control cabinet (metallic enclosure). Since each one of the plugs on their own does not have the required amperage, we are using t

I suggest a single common grounding bar.

Thanks for taking the time to respond. Are there going to be any concerns about this at all? ground loops for example?

 

[LarryFine]

Not for grounding, which should carry zero "normal" current. With rare exception, multiple grounding parts should be bonded.

 

[texie]

If it is wired in a compliant manner the question is moot as 1 EC grounding bar or 2 in the same enclosure the end result is the same. The enclosure is considered a compliant path.

 

[nimabakhshi]

If it is wired in a compliant manner the question is moot as 1 EC grounding bar or 2 in the same enclosure the end result is the same. The enclosure is considered a compliant path.

Thank you for your response. You are absolutely right, I even want to elude to that in my question but refrained. I think my question was mostly about code compliance and whether this is good practice in this specific situation or if we could somehow improve the work? Thanks again!