Encountering cut panel ground wires

Ah yes I forgot about amendments. I also forgot to look up the code today will do it tomorrow.

Is there any NEC rule that gives the maximum length of 4AWG grounding conductor wire that may be run from the panel to the location of the grounding electrode?
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Does the code now or in the past, allow the copper piping system to be used as part of the grounding conductor from the electric panel to the grounding electrode?

ie:
Panel box
4AWG wire to nearest point of copper pipe (say 12 feet away)
copper pipe runs thru house to well pump
near the pump, 4AWG wire from pipe goes into the wall penetration used by the well pipes
presumably to either a buried electrode, a metal well casing, or possibly down to be buried in the concrete foundation.