w_tom wrote:

One can attach electric service to the 10 foot buried water pipe as
an earth ground and will still fail inspection. Why? According to
new code, that facility still does not have an acceptable earth
ground. Water company may at any time replace that 10 foot of copper
pipe with plastic. Because this can happen, code says water pipe is
not a reliable earth ground. The code says that one of those four
items (Ufer ground, 10 foot rod, ground plate, etc) must also be
installed because THAT is the earth ground.

Again, not acceptable to dump electricity into pipes. Connections to
pipes (in some jurisdictions, that also includes gas pipe) is to
remove electricity from those pipes. Pity the poor plumber standing
in water only to discover the pipe he has just disconnected is
conducting electricity into earth. Just another reason why pipes are
connected only to *remove* electricity - not dump electricity into
them for the purpose of earthing.

NEC requires connection to water pipes - to remove electricity. That
is the change of philosophy that also requires a separate earth
ground installed only to be the earth ground. Without that dedicated
earth ground, a facility will not pass inspection.

If TPVFDP was correct, then that plumber standing in water would be
electrically shocked - a totally unacceptable situation. Earth
ground must be via something dedicated only for earthing; immediately
adjacent to breaker box and service entrance.

Now the technicals from code:

250.53(D)(1) Suppliemental Electgrod Required. A metal
underground water pipe shall be supplemented by an additional
electrode of the type specificed in 250.52(A)(2) through (A)(7).
...


(A)(2) through (7) are Metal frame of building, concrete encased
electrode (Ufer ground), ground ring, 8 foot ground rod, or buried
plate electrode.

IOW if water pipe is used for earthing, then another dedicated
electrode must also be installed. But if that other dedicated
electrode is installed, then water pipe earthing is not required. In
short, the water pipe is not sufficient for earthing.

Takoma Park Volunteer Fire Department Postmaster wrote:

There is no gentle way to say this. Your wrong. The only reason
I'm making an issue of this is so that no unsuspecting DIYer will
fail to make the required grounding electrode conductor connection
to the underground metal water piping and thus fail inspection. If
available on the premise there are four things that must be used as
grounding electrodes. These are A concrete encased electrode The
metal frame of the building A ground ring An underground metal
water pipe ten or more feet long.

In houses with a complete Pex water piping system and no interior
metal piping that could possibly become energized the connection to
the metal supply lateral from the water main is required by the US
NEC. In houses that have been remodeled so that most of the
interior water piping has been replaced with plastic you must make
two connections to the piping. One to attach a grounding electrode
conductor to the underground metal water piping and the other to
bond the remaining interior metallic piping to the grounded current
carrying conductor of the service. Both connections are required
by the US NEC.

You are one obstinate fella. How much electrical work have you done?
Once again I assure you that my only reason for making an issue of this
is that someone who relies on your advice can come to harm.

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. Where none of these electrodes
are available, one or more of the electrodes specified in 250.52(A)(4)
through (A)(7) shall be installed and used.
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.
(2) Metal Frame of the Building or Structure. The metal frame of the
building or structure, where effectively grounded.
(3) Concrete-Encased Electrode. An electrode encased by at least 50 mm
(2 in.) of concrete, located within and near the bottom of a concrete
foundation or footing that is in direct contact with the earth,
consisting of at least 6.0 m (20 ft) of one or more bare or zinc
galvanized or other electrically conductive coated steel reinforcing
bars or rods of not less than 13 mm (½ in.) in diameter, or consisting
of at least 6.0 m (20 ft) of bare copper conductor not smaller than 4
AWG. Reinforcing bars shall be permitted to be bonded together by the
usual steel tie wires or other effective means.
(4) Ground Ring. A ground ring encircling the building or structure, in
direct contact with the earth, consisting of at least 6.0 m (20 ft) of
bare copper conductor not smaller than 2 AWG.
(5) Rod and Pipe Electrodes. Rod and pipe electrodes shall not be less
than 2.5 m (8 ft) in length and shall consist of the following materials.
(a) Electrodes of pipe or conduit shall not be smaller than metric
designator 21 (trade size 3/4) and, where of iron or steel, shall have
the outer surface galvanized or otherwise metal-coated for corrosion
protection.
(b) Electrodes of rods of iron or steel shall be at least 15.87 mm (5/8
in.) in diameter. Stainless steel rods less than 16 mm (5/8 in.) in
diameter, nonferrous rods, or their equivalent shall be listed and shall
not be less than 13 mm (1/2 in.) in diameter.
(6) Plate Electrodes. Each plate electrode shall expose not less than
0.186 m2 (2 ft2) of surface to exterior soil. Electrodes of iron or
steel plates shall be at least 6.4 mm (1/4 in.) in thickness. Electrodes
of nonferrous metal shall be at least 1.5 mm (0.06 in.) in thickness.
(7) Other Local Metal Underground Systems or Structures. Other local
metal underground systems or structures such as piping systems and
underground tanks.

There is no way you can read NEC section 250-50 that allows you to avoid
using the underground metal water piping as part of the grounding
electrode system. That includes instances were the underground metal
service lateral is the only metallic pipe on the premises. It is true
that if the water piping is the only electrode available that it must be
supplemented by another electrode that is installed by the electrician.

It is also true that any plumber that opens a metallic service lateral
without checking for current and/or bonding around the work can get hurt
or even killed. I have attended two incidents of that kind as a
volunteer firefighter / rescuer. I have placed current transformers
around service laterals to demonstrate the danger to plumbers who were
about to begin working on them.

You have made the point repeatedly that a short connection to earth
ground is the heart and sole of surge and spike resistance for the homes
wiring system and the appliances attached to it. How many ground rod
impedance measurements have you done? I have done hundreds and I can
assure you that it is rare to find a two rod electrode system that is
under fifty ohms of impedance. I have also checked hundreds of
grounding electrode system impedances and I find that the impedance of
the water piping electrode is often ten ohms or less.
--
Tom H