Structure Bonding

[Smart $]

See the revised sketch. Unfortunately I don't know which is the service point. This is an industrial facility so I don't think we have any service, service drop, MBJ, etc. We only have a main bonding bar. Is the attached sketch Ok?

Here's my (simplified) sketch of your situation...

Anything with green is required. Assumes everything is (NEC) premises wiring equipment.

 

[Smart $]

...

Anything with green is required...

I should note there are a couple/few different options available for the copper/green lines. Perhaps I'll get around to those options later....

 

[Smart $]

I should note there are a couple/few different options available for the copper/green lines. Perhaps I'll get around to those options later....

Upon further consideration, you have no other option as long as the transformer electrodes are bonded to the main bonding bar and equipment bonding jumpers connect to any non-IG equipment. To use any of the alternatives would create a parallel grounded conductor path via the GES. In fact, as per your last sketch and mine, you already have multiple parallel paths. If you are interested in cleaning those up, let me know....

 

[kevin458]

Thanks, it makes more sense now. I did not know that in NEC, the connection of electrode of transformer 1 to the electrode of transformer 2 was optional. Yes please remove the parallel paths in your diagram that you have mentioned.

 

[Smart $]

Thanks, it makes more sense now. I did not know that in NEC, the connection of electrode of transformer 1 to the electrode of transformer 2 was optional.

It's not optional. There are basically two frames of thought for your situation: 1) each transformer has a GES as a separate structure, or 2) the transformers electrodes are part of the building GES.

In case 1, the building is required to have its own GES. Nevertheless, all the separate GES's would be connected together through required, non-GEC grounding conductors.

Case 2 requires the electrodes be bonded together to form the building GES and appears to be the frame of thought in your situation.

Yes please remove the parallel paths in your diagram that you have mentioned.

I don't know for certain what I was thinking when I wrote that. There's obviously parallel grounding conductor paths, and I think at the time that bled over into parallel grounded paths... quite errantly on my part. There likely will be some grounded [neutral] conductor current on the grounding system, but an inadvertent result and unavoidable consequence of compliant grounding.