whit3rd wrote:
On Nov 23, 5:38 pm, D Yuniskis wrote:

Grounding the mains to "plumbing" *was* common in the US many
years ago. Now, I believe, you *must* ground to a metal
rod driven into the earth (8 ft?).

Just to be clear, my copy of the US National Electric Code clearly
requires (section 250-80) plumbing to be bonded to the electrical
service ground, it just doesn't allow the buried water piping to
substitute for a ground rod or similar to-the-soil connection.

Exactly. And the housing of the circulating pump for your
swimming pool must be grounded as well. But, you don't ground
the *mains* through your circulating pump! :

The Code tries to anticipate things that *could* become
electrified and grounds them. E.g., exposed beams in a metal
building, etc. But, it doesn't let you use those things
*as* ground!

The ground wire from the interior water pipe grounds the pipes, not
the electric wiring.

Exactly.

However, in years (decades) past, it was common to use the
water main as the ground for the incoming service. This isn't
a reliable way to "earth" the mains (for a variety of reasons).

If you poke around people's homes, you will see all sorts of
"questionable practices" wrt ground. Its a wonder more folks
aren't electrofried! :