Doug Miller wrote:
In article , AZ Nomad wrote:

On Mon, 31 Jul 2006 19:33:04 GMT, Doug Miller wrote:



In article . com, "Brad"

wrote:

Both pipes should be at the same electric potential (ground) since
they are both are buried.
The grounding is done to help ensure the electrical panel has a true
ground.

Wrong, wrong, wrong, wrong.

The water piping is bonded to the electrical ground in order to insure that
the _water_piping_ has a true electrical ground -- IOW, to prevent the water
piping from becoming live in the event of an electrical fault somewhere.

The first poster had it right. The water piping is already at ground because
it is in direct contact with the ground. Unless of course you have
your water brought to you on pipes suspended in the air. Or perhaps you
have it flown in?


No, he didn't. 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.

BTW... have you ever heard of plastic water piping?


The NEC has for a very long time required that water service pipes be
used as a grounding electrode. The current code REQUIRES that water
service pipe with metal pipe underground length of 10 ft or more be
included as a grounding electrode. Because this pipe may in the future
be replaced with plastic pipe, a supplemental electrode is required -
usually ground rod(s). For new construction use a Ufer ground/concrete
encased electrode. These electrodes are connected together to make a
grounding electrode system. The earthing resistance of a metal municipal
water system is lower than anything you can provide in a house.

bud--