Mark,
All three grounded conductors are connected together. The only difference in the current on any of the conductors will be based on the impedance of the path. There will only be very small differences in the impedances and therefore only a small difference in the current flowing in each grounded conductor. I agree that you will have little current in the grounding electrode conductor between the last panel and water pipe. Take an example of a condition where there is 50 amps of unbalanced current in panels 1 and 3 and 20 amps in panel 2. In this case you would have 10 amps on the grounding electrode conductor from 1 to 2 and from 3 to 2 but each grounded conductor would have 40 amps. If the unbalanced current was 60 on panel 3 and 0 on the other 2 panels, you would have 40 from 3 to 2 and 20 from 2 to 1. Unless there is a problem with one of the grounded conductors between the transformer and the panels, the grounded conductors will never be over loaded.
Don(resqcapt19)
[This message has been edited by resqcapt19 (edited 03-16-2002).]
