This are definitely interesting, and it was detected currents in the ground in Oslo when the subway in Stockholm in 1950 was started. (417 kilometers away and supplied with 750V DC)
Still this are considered as a non existing problem.
I'm a educated as a mechanical engineer, but have dealt pretty much with electro...
When we consider our traditions with IT systems, these problems are not of importance .... ????
I see lots of equal sides to your 277/480V systems, and your 208 delta's
Perhaps not an apparent problem, but IMO a step back. 230 volt IT does not produce stray currents since all load current is carried on insulated conductors, but the system that replaces it with TN-C-S does. Backwards IMO for one of the most advanced countries on Earth.
Personally I would use TN 3x230+PE for home and light commercial networks while using TN-S 400Y/230+N+PE for large commercial/industrial.
Our 208 volt system are not delta rather 120/208Y. Our deltas are 240 volts but rare in new construction. Both our 277/480 and 120/208 is TN-C-S. TN-C is used everywhere by utility companies even in the high voltage side. Never liked it but that is how it is.
