Here's what I have ... an service consisting of (2) 400A, 120/240V, 1ph panels, each being fed with (2) 250kcmil copper per phase and neutral. I have a 4" metal water pipe (more than 10' in contact with earth) and a #5 rebar stubbed out of the footing as my grounding electrodes. I want to set up my grounding electrode system this way ... mount a 1/4" thick x 2" wide x 6" long aluminum bus on the wall above the lay-in ceiling at the service location. A 2/0 copper GEC will run from the 4" water main to the grounding bus. A #4 solid copper GEC will drop down and connection to the rebar. One 1/0 copper GEC will connect from the grounding bus to the neutral bar in each of the (2) 400A panels. (one 1/0 for each panel) The GECs will connect to the bus with standard one-hole lugs bolts to the bus bar. Does anyone see a problem? This seems to be allowed under the new language of 250.64(C)(3) in the '05 NEC. Other than the bus and all connections being accessible, is there any other consideration to look at?
