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. Yes, that water pipe must be bonded to the AC
electric so that plumbing is electrically same voltages as everything
else inside the house - human safety. Public utility water system may
have voltages different from AC electric if the two are not bonded -
as has been observed when a fault was created outside the building.
Destructive currents entering on that water system must be eliminated
by being bonded to AC electric.

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.

For lightning, an antenna (or satellite dish) is typically treated
as if a separate structure as demonstrated in this application note:
http://www.erico.com/public/library/...es/tncr002.pdf
Antenna wire must connect to the same building 'single point' earthing
electrode. IOW any wire in any cable going to the station must first
connect to that single point earthing electrode (either by hardwire or
protector) before entering the building. Best is to have the antenna
earthing also connected, by underground wire, to that same single
point ground.

This for lightning protection is beyond what is called for by
National Electrical Code for numerous reasons. First, NEC only
addresses human safety. The OP is asking about transistor safety.
Second, the code does little to address impedance. Grounding for
human safety is mostly about resistance - not impedance. Third, any
grounding system dependent on some other trade (ie plumber) is no
longer considered safe or sufficient.

A ground system must meet NEC requirements. Then it must exceed
those requirements. For lightning protection, a cold water pipe is
not longer considered a good solution because that earthing electrode
is just not sufficient.

Also better is to earth lightning rods and antennas before that
ground wire connects to a building's single point ground. Notice the
underground wire connection between antenna earth ground and building
earth ground.

And finally a purpose of earthing that is beyond what the NEC
requires. A station needs earthing that provided both equipotential
and conductivity. Code concentrates on conductivity. But for
equipotential, we do things beyond what is normally sufficient for
human safety. We install Ufer grounds or halo grounds that completely
surround the protected facility. We relocate all utilities so that
each wire in each cable makes a 'less than 10 foot' connection to that
common earth electrode. Any exception to the single point earth
ground (as defined in code) is not permitted when also earthing for
transistor safety. Route earthing wires to be separate from all other
wires, no splices, no sharp bends, not inside metallic conduit, etc.
All earthing wires remain electrically separate until all meet at the
single point ground. Conditions beyond what code demands or permits.

Consider with care information in that figure in:
http://www.erico.com/public/library/...es/tncr002.pdf
Things recommended are not immediately obvious. Reasons for this
involve both equipotential and conductivity. Both are required for
station protection.

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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