On 10/7/2012 9:40 AM, dpb wrote:
On 10/7/2012 10:54 AM, bud-- wrote:
On 10/6/2012 11:48 AM, dpb wrote:
...

Not only is it allowed, it is *required*.

Only three electrodes are *required* to be used as earthing electrodes -
if present.

One is a water service pipe (10 ft ...).

...

The key words there are "if present".

It certainly is _NOT_ part of NEC that there is _REQUIRED_ to be 10-ft
of metallic water service pipe.

Of course not.


What is required is that any metal plumbing system that is present be
bonded _TO_ the earthing system (since 1978) but as noted, a metal
plumbing system of whatever length is NOT, by itself, Code-compliant
(again, since 1978).

For at least 50 years the NEC has required a "supplemental" electrode
for water pipe electrodes *if* the water service pipe was likely to be
replaced by plastic. The 1978 change required a "supplemental" electrode
on all new installations.

If there is a plastic water service, the metal water pipes in the
building must be "bonded" to the electrical system. There are separate
rules for "bonding".

But the basic requirement has not changed - if there is 10 ft of water
pipe in the earth the pipe is *required* to be used (and connected) as
an earthing electrode (not "bonded"). The earthing electrode is always
a "system" which may be one electrode, or several may be required and
others can be added. A metal water service pipe (10 ft...) is one of the
electrodes that is *required* to be included.

If the water pipe is not included as an earthing electrode the
installation is clearly not "code-compliant".