we have an 800 amp main disconnect feeding 3 200 amp and 1 300 amp subpanels they are fed with 4/0 copper with #2 copper gec Main is grounded with #4 copper to 3 ground rods Subpanel is boned to water line with #4 cooper The engineer who designed this setup wants each sub to have #6 copper to a ground rod This does not seem right Any comments?