However, a copper grounding system would die under certain conditions. I have been working for a company the processes foundry wastes from aluminum foundries. Among other things this stuff releases more in the way of ammonia gas than does barnyard waste and the ammonia is murder on copper wiring.

Our wastewater treatment building also knows how to corrode stainless steel. Ammonia plus forms of chlorine such as fluxing salts makes for a complexing agent that dissolves the nickel in stainless steel. This in turn allows the ammonia to directly dissolve the chromium component. The iron component then rusts away. For that matter, tin plated copper and tin plated aluminum is corrosion resistant in our environment EXCEPT for the wastewater treatment room and possibly the soil around our material receiving room.

In our case a grounding electrode system would need to use active electrolytic corrosion protection using carbon anodes that are about 20 to 60 feet from the grounding rods and plates. The positive side of say a 5 volt DC supply would would be connected to the carbon anodes and the negative side to the electrical grounding system.

Oh, one thing that I have learned is that 480 volts ungrounded 3-wire 3-phase that is in PVC conduit picks up a heck of a lot of destructive static electricity during rain storms, what is known as Saint Elmo's Fire.

Mike Cole, mc5w at earthlink dot net