2023 NFPA 70B Grounding and Bonding Fundamentals 

Thank you!

Hello! Here is the link for the ground testing guide: us.megger.com/promotion/download/electrical-testing-standards-guide

For systems with multiple grounding electrodes, it's considered best practice to bond them directly underground to ensure both electrodes are at the same electrical potential. For example, imagine you have two grounding electrodes on opposite ends of a large ground-mount site. If the electrodes are bonded underground, they have a direct low-resistance path for current to flow between them and for the voltage between the two electrodes to equalize. On the flip side, if the electrodes were only connected by the aboveground EGCs and bonding jumpers, the path for current to flow to equalize the voltage across both electrodes would go through the inverter, array, and other onsite power electronics. Ideally, we want all electrodes to remain at our reference "ground" voltage, which is best accomplished by bonding them together.

Typically the service/GEC are hundreds of feet away from the ground mounted PV array. Seems easier said then done with tying the two GEC together. @@MayfieldRenewables

That's correct - technically, the module frame would be energized from the fault and the inverter GDFI would pick this up. The dashed red line was chosen for ease of illustration and to show the fault path through earth.