Proctologically Violated©® wrote:

Awl--

How much is acceptable?
An amp-probe reveals between 2 and 6 amps, depending on how balanced the
load is on each leg of the main panel.
I'm hearing that the neutral from the panel is connected to a *steel* cable
outside, while the hots are indeed connected to copper conductors. This
would explain some current going through ground.

If the water main connection is broken, no noticeable effect in the
house--or so it seems.

Mebbe I'll amp-probe some of my neighbors plumbing.
--

Time to call the utility.

An open or high-resistance neutral from pole to your
home can cause the neutral unbalance current to flow
via the copper water main piping to your neighbor's
neutral and then back to the pole (as you suspected).

In all likelihood it's the utility's responsibility,
not yours.

It's a serious issue because unexpected neutral currents
can cause overheating of any of the parts in the
"grounding" path.

Jim