I'm installing a 480/120/240 single phase transformer to feed a 150 amp panel 120/240 in a remote wood building which is a air compressor room no steel to bond to 200' away from the main service. Do I need to run a 3/0 from the building steel of the plant which the main service is grounded to to bond the transformer or is two ground rods all I need.
I think all you "need" is two 8' ground rods on a 6 gauge GEC. You could make that better with longer rods or a ground ring. I am not sure where a plate ranks because I have never seen one or heard much about them. I know of no rule that requires running a 250.66 GEC back to the other building. At 200', voltage drop will need to be in your calculations tho
