Roger, in the above post I made, this is the situation:
800a MDP, 480/277V, parallel 500mcm with parallel 350mcm nuetral. No bond to building steel in MDP, or bond anywhere for that matter. Under 250.66, don't you take the largest ungrounded conductor in each parallel set and add the circular mills together, and using the chart in 250.66, that comes out to a 3/0? Where did I go wrong?
Next question, If I bond this service to the steel, and water pipes, sprinkers ect, and this GEC terminates in the MDP, where I bond it to the nuetral, I can't use this bus to bond the nuetral of a 480X208/120Y? The Egc would be the Emt and Flex, but I can't run a GEC from the bus of the MDP to the transformer, I have to run its own seperate GEC to building steel?
Make sense I hope.