Thank you for your question. Primarily, the ground conductor needs to be able to handle the calculated fault current of the system, so that the fuses and/or breakers can function properly. Typically, we see separate ground wires run for each building, as you would not want a fault in one building to impact another. Nor would you want a single damaged ground wire to negate the circuit protection for every building in the system.
Beyond simple electrical faults, there are many other valid reasons for installing separate ground wires when one considers signaling noise, harmonics and transients. Let alone lightning strikes which could send massive amounts of electrical energy down the ground wire to wherever it is installed.
We recommend you run bare copper wire, sized to handle the anticipated fault current, buried in direct contact with the earth, to each of the main electrical services from the source. You should follow all applicable rules regarding depth of the conductor based on the frost-line of the area you are in.
We hope you find this information useful. If you should have any further questions, please do not hesitate to contact us again.
The Engineering Team at E&S Grounding Solutions
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