SoundMods wrote:
I imagine that if you get enough electricians hauled away in a stretcher -- the requirements change.
Not just electricians on stretchers.
When Tom P. Walt and I were little kids, the standard used to ground an electrical service in a single family home was by connecting to the cold water pipe. No supplemental grounds were used. In that time frame, cold water pipes would have been galvanized pipe (with yummy lead inside) or copper tubing. So, the electrician installed a GEC (grounding electrode conductor) from the panel to the most convenient water pipe.
Three things happened. 1) A plumber repaired or replaced a section of pipe, maybe made a new tap for a new plumbing fixture. He shut off the water and cut the pipe in the basement ceiling over his head. He gets wet, and when he separates he pipe between his two hands, he becomes part of the service ground. Zap, one less plumber. 2) The connection was made to a hot water pipe and a new water heater was installed with non-metallic piping inside. No service ground in the house. Very bad for occupants. 3) That nasty old galvanized piping gets replaced.......with PVC or PEX. Again, no service ground in the house. Danger Will Robinson.
So, Code evolves, as Tom and Walt pointed out, due to dead plumbers and shocked, or worse occupants. Now we connect to cold water within 5' of the point of entry of piping to the house 250.68(C)(1). Where I work, we try very hard to make the connection closer to the point-of-entry than that. Also we try to connect ahead of the water shutoff whenever possible. AND we are required to use at least one ground rod (PG County requires two ground rods), so we minimize the chance of harming a plumber or homeowner working on household piping.