DS,
If I bond to the interior piping at any readily accessible point(s) with electrical continuity with #4 copper, and I am not counting the the main (the part that is buried outside) as one of my electrodes, and my main is bonded with an inaccessible or very difficult #6 and cannot be contacted by any conductor over 50 A, do I need to run a #4 to the main itself, e.g., within 5' of point of entry, in order to upgrade to 200 A service?
I want to just say yes, you must, but 250-50 uses the words "if available" in the requirement to use the metal underground water pipe as a grounding electrode, so this would be a call of your AHJ. I would not, if I was the AHJ, waive this requirement just because it is "very difficult" to get to the water pipe within 5' of entry.
Don(resqcapt19)
