DS
I simply assume that I need two ground rods for my primary (permanent) electrode system.
Even if you use the water pipe 2 ground rods are requires unless you can prove that a single rod complies with the 25 ohm rule in 250-56
I don't count it as a primary electrode for a number of reasons.
At this time the code does. There are a number of reasons not to use the metal underground water piping system as a grounding electrode, but CMP5 has not yet agreed with those reasons.
The comments by Mr.Schiff about not using the metal underground piping as an electrode to improve safety of water department workers are not correct. If we stopped using it as the grounding electrode, but still bonded it to the grounding system inside the building the same safety problem will exist. The only way to improve safety for the water department workers would be to use a dielectric fitting in the water service to isolate the interior and exterior parts of the metal piping system. This is often done by gas utilities that are still using metal pipe for exterior gas supply lines.
Don(resqcapt19)
