Redsy, here a picture for you...
http://www.markhellerelectric.com/25024.pdf Many linemen see grounds as a hazard, it seems. They seem to think that if the ground comes loose it will fall on the live busses of the meter, and KaBoom. (It could happen in a main the same way) Some PoCo's don't see the meter as "accessable" because they lock it, ours are just a wire, or lollipop seal.
The way I see it, if there is a bonding or ground failure in a set up where the GEC is in one panel, the other panel and the meter base is lost. Another reason I like "all-in-ones".
Anyway, what shortcircuit's getting at is, with a #4 GEC you're limited to 3/0 SEC's making it a 225A service if
it were a single family dwelling. For a 320A continous, youd need 350MCM SEC's, with a #2 GEC. And another size up for 400A even.
