I agree in principle with that gfretwell, but I don't recall ever seeing a requirement about distance for electrodes in the NEC (Often its hundreds of feet to the cold water from the switch gear on projects I work on).
Other than the 25 ohm requirement for ground rods, which will not ever be obtainable if you have too far a run with your GEC. But as we all know, you can bypass that requirement by driving a 2nd ground rod.
