"Nate Nagel" wrote in message

stuff snipped

Next thing to check for is a heavy bonding wire between the same area
and the main electrical panel. (was the main feed from the city water
line originally copper or galvanized but recently replaced with PVC?)

It's clear why grounding to water pipes isn't the great idea it used to be
even though in many old houses (like mine) you'll still find plenty of
clamps attached to supply lines. The mains could be PVC, repairs in the
house, even if it has copper plumbing could be plastic, etc.

Undertrained, underpaid cable jockeys find it's a hell of lot easier to
ground a CATV line to a nearby water pipe than it is to run a cable to the
circuit box where you can attach to a proper grounded conductor. A defect
in the attached equipment can then energize the section of isolated pipe
without tripping a breaker, which might be what's happening here.

--
Bobby G.