Bear in mind the NEC says a Ufer is only worth a #4 cu GEC.
I think the code says quite the opposite. No matter what size the switchgear is a #4 is enough.
Lets make the question a little simpler. You have 1200 kcmil SEC. You have a #4 copper as a ufer. You attach 3/0 from the switchgear to start of the ufer. At the other end of the ufer you attach 3/0 and bond to cold water. Is this legal?
I personally think the code allows this by 250.62(F), while I consider it wrong.
