When a metal underground water pipe is used as a grounding electrode, what else is required?

Giải thích

A water pipe electrode is never allowed to stand alone because plastic repairs or dielectric fittings can silently disconnect it from earth, so it must always be supplemented by another qualifying electrode such as a rod or a concrete-encased electrode. Pipe length does not remove the requirement, gas piping is bonded but is not permitted as an electrode, and the 25-ohm test applies to rod, pipe and plate electrodes.