While examining my mother's fuse panel, I started wondering about the grounding system. Her house was built about 1960, and has a 100 amp fuse box on the inside basement wall, with a 100 amp cartridge fuse disconnect outside beside the meter. I noticed that the outside box has a bare ground wire which runs in to the fuse box, then up to the cold water copper tubing which runs above the fuse box. There is no ground rod driven into the soil. Is this an appropriate method of grounding the service panel? I wonder about the continuity of the copper plumbing, particularly where there is a pressure regulator in the line. Should this go to a ground rod in the soil rather than being clamped to the water system?

Back when all water distribution was metal that was the best grounding electrode. The whole city was tied to the same equipotential grid. Now that everything is plastic that is no longer true so we have the requirement for the supplemental electrode. I would drive a rod and connect it to the panel. If there is any question about the conductivty of the pressure regulator (not all metal body) jumper around it.