w_tom wrote:

On Apr 2, 8:07 am, Roger wrote:

Ahhh...The water pipe must be bonded to the electrical system, but the
main ground must be at the entrance. Here, we have plastic water pipe
all the way to the main from the meter, yet we have to bond the meters
which are metal with plastic running in and plastic running out.
...

It's really easy to avoid here. We do not have metal piping available
for grounding.
Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)www.rogerhalstead.com


Roger is correct here. Underground water pipe electrode is no
longer sufficient as the earth ground in most locations for a long
list of reasons.

As Thomas said, Roger is correct if the underground water service pipe
is plastic.
Missing is any of the “long list of reasons”.


Many other reasons why AC breaker box must be bonded to the cold
water pipe. Yes cold water pipe may act as an earthing electrode.
But it is no longer sufficient as the earthing electrode.

An earthing electrode - one that all utilities must use - is not the
water pipe. All utilities must connect to a separate and dedicated
earthing electrode defined by code (as defined in Article 250.52 A -
paragraphs 2 through 7). The code defines 7 types of earthing
electrodes. The only electrode not sufficient is cold water pipe -
paragraph 1.

The code says (250.50) all electrodes listed in 250.52-A-1 through 6
MUST (where present) be connected together to form the earth electrode
system. 250.52–A-1, which is conveniently missing from w_’s list, is
metal underground water pipe (at least 10 feet metal underground).

ONLY if the pipe is not 10 feet long underground is bonding used instead.

Water pipe requires a “supplemental” electrode. That is because the
metal pipe may in the future be replaced by plastic.
From the National Electrical Code Handbook - same publisher as the NEC
“The requirement to supplement the metal water pipe is based on the
practice of using plastic pipe for replacement when the original metal
water pipe fails. This leaves the system without a grounding electrode
unless a supplementary electrode is provided.”

Requiring a supplemental electrode does not indicate there is any defect
in metal pipe as an electrode. As Thomas indicates, it is likely by far
the best electrode available in urban areas with metal supply.

Earthing connection of other services, like the phone NID, may be made
to the water pipe within 5 feet of the entrance to the building (the
connection of the power earthing conductor is in the same 5 foot span).



We install Ufer grounds or halo grounds that completely
surround the protected facility.

From
http://www.lightningsafety.com/nlsi_...finitions.html
“Halo Grounded Ring: A grounded No. 2 wire, installed around all four
walls inside a small building, at an elevation of approx. six inches
below the ceiling. There are drops installed from the halo to the
equipment cabinets and to waveguide ports, interior cable trays etc.
Halo rings serve as connector points to achieve ground references of
interior metallic objects. These, in turn, are connected to the main
ground bus bar.”

Perhaps you mean “ground ring”?


----------------
The code now requires a Ufer electrode in new construction with concrete
foundations or footings.

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