Minnie Bannister wrote:
But one other question comes to mind: can I really believe/assume that
these existing grounds are all connected together already? Is there
really a conductor running the 60ft or more from the gas meter and
telephone interface at one end of the house to the electricity meter at
the other end? How can I be sure?

Measure the AC voltage between them. Different grounds differ by some part
of a volt (AC). That's a one-way test, to tell they're
definitely not connected if you see voltage.

I get a half volt (AC) just between a couple of ground stakes driven into
the yard, anyway. If lightning hit nearby, it would be thousands, which is why you
don't want two unbonded grounds inside the house together.

Set the meter on AC not DC. The voltage you see is from power grid grounds
reconciling themselves in the earth so it's AC too.
--
Ron Hardin


On the internet, nobody knows you're a jerk.