Doug Miller wrote:
In article , Bud-- wrote:

Your fact is not consistent with what you said:
�The electrical system has its own, *separate* grounding electrode.
Metal water piping is bonded to the electrical system grounding
electrodes to ensure that the metal water piping cannot become live,
*not* to provide a ground for the electrical system.�

I do not see how "*not* to provide a ground for the electrical system"
can be read other than the water pipe is not to be a grounding electrode
and the system grounding is provided by the system's "own, *separate*
grounding electrode."

It's real simple: the water pipe is bonded to the other grounding electrodes,
not to provide a ground for the electrical system -- that's what the *other*
electrodes are there for, remember? -- but to ensure that the metal water
piping is always at the same potential as the electrical system's ground and
therefore cannot become live no matter *what* might go wrong electrically.

I'm sorry that you're having such a hard time grasping this... but you really
need to spend a little more time educating yourself before you post again.


"250.50 Grounding Electrode System.
If available on the premises at each building or structure served, each
item in 250.52(A)(1) through (A)(6) shall be bonded together to form the
grounding electrode system.
250.52 Grounding Electrodes.
(A) Electrodes Permitted for Grounding.
(1) Metal Underground Water Pipe. A metal underground water pipe in
direct contact with the earth for 3.0 m (10 ft) or more (including any
metal well casing effectively bonded to the pipe) and electrically
continuous (or made electrically continuous by bonding around insulating
joints or insulating pipe) to the points of connection of the grounding
electrode conductor and the bonding conductors. Interior metal water
piping located more than 1.52 m (5 ft) from the point of entrance to the
building shall not be used as a part of the grounding electrode system
or as a conductor to interconnect electrodes that are part of the
grounding electrode system." Copyright 2002 National Fire Protection
Association

Now who is it that needs to educate themselves?
--
Tom Horne

"This alternating current stuff is just a fad. It is much too dangerous
for general use." Thomas Alva Edison