I'm not sure I understand all parts of the question but based on what I do understand I would say that GEC required based on 250.66 would be 3/0 copper or 250 aluminum. This is based on having parallel 500 kcmil Service Entrance conductors. I am confused by the statement "Delta/Y Service". Is it a Delta or a Wye? Next I guess depending on how you routed the GEC, you could run the large GEC to the water pipe and building steel then run a smaller wire (#6) to the plate and rod as a supplement.
The plate and rod are optional electrodes since the water pipe would have a supplement with the building steel. Assuming the water pipe and building steel qualify as grounding electrodes. 250.52(A)(1)(2)
I don't know where his Service conductors are located- Whether he has a step up Xformer or step down or where his GEC originates. Need to have this info to really size the GEC. Customer owned Xformer? Service point?
Last edited by George Little; 09/16/08 08:37 AM.
