Hello:

Was just wondering about this a bit.
Live in the Boston area, in a typical Colonial built about 30 yrs ago.

Have the "standard" 220 V line coming into the house from the street line
Appears to be 3 conductors, the 2 phases and the neutral.

My question is that I keep reading about houses needing, and the NEC
requiring, a ground (or grounding) rod right outside
the house.

Don't seem to have one.

Is an actual ground rod required ?
Where would it be ?

If not, why not ?

Thanks,
Bob

Robert11 wrote:
Hello:

Was just wondering about this a bit.
Live in the Boston area, in a typical Colonial built about 30 yrs ago.

Have the "standard" 220 V line coming into the house from the street line
Appears to be 3 conductors, the 2 phases and the neutral.

My question is that I keep reading about houses needing, and the NEC
requiring, a ground (or grounding) rod right outside
the house.

Don't seem to have one.

Is an actual ground rod required ?
Where would it be ?

If not, why not ?

Thanks,
Bob


Not required 30 years ago.

More than likely the water service line to the street
is metallic and the electric service has been grounded to that.
If so, it makes a much more effective ground than a driven ground rod.

Jim

That earthing electrode has been required since 1990s.
Water pipe is no longer acceptable as an earth ground (not to
be confused with other grounds such as the safety ground that
centers inside mains break box). That dedicated earth ground
adjacent to breaker box is a solution to numerous technical
problems. That earth ground rod being minimal grounding.
Some require more than just a single rod. All other incoming
utilities (telephone, cable, satellite dish) must make a less
than 20 foot connection to the same earthing - per code. In
reality, you want each connection to be less than 10.

Robert11 wrote:
Was just wondering about this a bit.
Live in the Boston area, in a typical Colonial built about 30 yrs ago.

Have the "standard" 220 V line coming into the house from the street
line Appears to be 3 conductors, the 2 phases and the neutral.

My question is that I keep reading about houses needing, and the NEC
requiring, a ground (or grounding) rod right outside
the house.

Don't seem to have one.

Is an actual ground rod required ?
Where would it be ?

If not, why not ?

Thanks,
Bob

Robert11 wrote:

Was just wondering about this a bit.
Live in the Boston area, in a typical Colonial built about 30 yrs ago.

Have the "standard" 220 V line coming into the house from the street
line Appears to be 3 conductors, the 2 phases and the neutral.

My question is that I keep reading about houses needing, and the NEC
requiring, a ground (or grounding) rod right outside
the house.

Don't seem to have one.

Is an actual ground rod required ?
Where would it be ?

If not, why not ?

Thanks,
Bob
w_tom wrote:
That earthing electrode has been required since 1990s.
Water pipe is no longer acceptable as an earth ground (not to
be confused with other grounds such as the safety ground that
centers inside mains break box). That dedicated earth ground
adjacent to breaker box is a solution to numerous technical
problems. That earth ground rod being minimal grounding.
Some require more than just a single rod. All other incoming
utilities (telephone, cable, satellite dish) must make a less
than 20 foot connection to the same earthing - per code. In
reality, you want each connection to be less than 10.


W Tom
You keep making that statement even though you've been corrected several
times. It is a disservice to the DIY community to repeatedly say "Water
pipe is no longer acceptable as an earth ground." The US National
Electric Code (NEC) requires that any underground metal water pipe that
is ten or more feet in length shall be used as a grounding electrode. I
know that you will now try to muddy the water by bringing up the
requirement for a supplemental electrode but the fact is that regardless
of how many electrodes you have you must use the underground metal water
pipe as a grounding electrode if it is available on the premise. You
can argue all you want but until the Code Making Panel that is
responsible for chapter 250 of the US NEC changes the code underground
water piping must be used as a grounding electrode in any locality that
has adopted the NEC as that localities code.
--
Tom Horne

"This alternating current stuff is just a fad. It is much too dangerous
for general use." Thomas Alva Edison

"Commodore Joe Redcloud©" wrote in message
...
On Thu, 29 Dec 2005 19:49:52 GMT, "Tom Horne, Electrician"
wrote:

Tom Horne

"This alternating current stuff is just a fad. It is much too dangerous
for general use." Thomas Alva Edison

For those who don't know, Edison's first working municipal electrical
system was DC.


Commodore Joe Redcloud©

That's exactly why he said ac was dangerous. He had a vested interest in the
use of DC.

Bob

Robertm wrote:
"Commodore Joe Redcloud©" wrote in message
...
On Thu, 29 Dec 2005 19:49:52 GMT, "Tom Horne, Electrician"
wrote:

Tom Horne

"This alternating current stuff is just a fad. It is much too dangerous
for general use." Thomas Alva Edison

For those who don't know, Edison's first working municipal electrical
system was DC.


Commodore Joe Redcloud©

That's exactly why he said ac was dangerous. He had a vested interest in the
use of DC.

Bob
Which he actually developed into the electric chair:
http://inventors.about.com/od/hstart...tric_Chair.htm
'Course DC is no fun either, talk to the guys who work on the CTAs "L"
trains. They told me about pulling an arc in a light socket replacing
a bulb, nothing to do but walk away from it.
Richard

On Thu, 29 Dec 2005 14:09:20 -0600, "Robertm"
wrote:


"Commodore Joe Redcloud©" wrote in message
.. .
On Thu, 29 Dec 2005 19:49:52 GMT, "Tom Horne, Electrician"
wrote:

Tom Horne

"This alternating current stuff is just a fad. It is much too dangerous
for general use." Thomas Alva Edison

For those who don't know, Edison's first working municipal electrical
system was DC.


Commodore Joe Redcloud©

That's exactly why he said ac was dangerous. He had a vested interest in the
use of DC.

Bob


And, considering what he wanted AC to be used for, "Westinghouse" was
once a synonym for "electrocute".
--
Mark Lloyd
http://notstupid.laughingsquid.com

"Democracy is two wolves and a lamb voting on what
to have for lunch. Liberty is a well armed lamb
contesting the vote." - Benjamin Franklin

You have it backwards, Tom. Previously you made that
claim. Others then noted why you were wrong. Even if a home
is earthed by a water pipe, that water pipe is no longer
sufficient for earthing (exception is legacy conditions). The
code requires bonding to water pipe - grounding for human
safety. The code is quite specific as to what is required for
an earthing electrode.

I don't expect to change Tom Horne's opinion - having
previously quoted code. But for the benefit of others, the
code says in Article 250.53(D)(2):
Supplemntal Electrode Required. A metal underground water
pipe shall be supplemented by an additional electrode of a
type specified in 250.52(A)(2) through (A)(7).

Those six electrodes are 2) Metal Grame of the Building or
Structure, 3) Concrete Encased Electrode (also called Ufer
grounds), 4) Ground Ring (also called Halo ground), 5) Rod and
pipe Electrodes (also called a copper clad ground rod), 6)
Plate Electrodes, or 7) Other Local Metal Underground Systems
or Structures.

If earthed only to a water pipe, then a building does not
have sufficient earthing. If no water pipe exists, any of the
above ground electrodes 2 through 7 are sufficient - need not
be supplemented. The water pipe is no longer sufficient for
earth ground which is why it must be "supplemented". The
Original Poster is advised to install earthing as required by
post 1990 code. This for two reasons - human safety (per
code) and transistor safety (which code does not address).

Building's occupants also want transistor safety.
Therefore a second reason why water pipe earthing is often
insufficient as an earth ground.

The code says water pipe earthing (which was standard before
19909) is insufficient. Appliance protection also demands an
adjacent earthing electrode for other reasons electrical. Two
reasons why water pipe earthing is no longer sufficient. NEC
requires water pipe be bonded to AC electric safety ground -
for human safety reasons. NEC requires other electrodes (2
through 7) for earthing.

Robert11: volts500 also posted a description of other
safety grounds in a post entitled "Grounding Rod Info" in the
newsgroup alt.home.repair on 12 July 2003 at
http://tinyurl.com/hkjq

"Tom Horne, Electrician" wrote:
W Tom
You keep making that statement even though you've been corrected
several times. It is a disservice to the DIY community to
repeatedly say "Water pipe is no longer acceptable as an earth
ground." The US National Electric Code (NEC) requires that any
underground metal water pipe that is ten or more feet in length
shall be used as a grounding electrode. I know that you will now
try to muddy the water by bringing up the requirement for a
supplemental electrode but the fact is that regardless of how
many electrodes you have you must use the underground metal water
pipe as a grounding electrode if it is available on the premise.
You can argue all you want but until the Code Making Panel that
is responsible for chapter 250 of the US NEC changes the code
underground water piping must be used as a grounding electrode
in any locality that has adopted the NEC as that localities code.

On 29 Dec 2005 12:33:59 -0800, "spudnuty" wrote:


Robertm wrote:
"Commodore Joe Redcloud©" wrote in message
...
On Thu, 29 Dec 2005 19:49:52 GMT, "Tom Horne, Electrician"
wrote:

Tom Horne

"This alternating current stuff is just a fad. It is much too dangerous
for general use." Thomas Alva Edison

For those who don't know, Edison's first working municipal electrical
system was DC.


Commodore Joe Redcloud©

That's exactly why he said ac was dangerous. He had a vested interest in the
use of DC.

Bob
Which he actually developed into the electric chair:

Which is why his opponents, the competing company, were able to say
that DC was dangerous,

http://inventors.about.com/od/hstart...tric_Chair.htm
'Course DC is no fun either, talk to the guys who work on the CTAs "L"
trains.

That's where the metaphor got started, that abortion or social
security or whatever is the "third rail" of American politics. The
third rail, touch it and you die, referring to the power rail on an L:
or subway.

They told me about pulling an arc in a light socket replacing
a bulb, nothing to do but walk away from it.
Richard

There's a bronze plaque in Lower Manhattan, NYC, where Edison's
original power station was, but no museum or anything. Not worth
going out of one's way for, unless you're really devoted to "being
there". But there are other things to sightsee there, and the
location would be in history books (but probably not in NYC tourist
books.) (It's 2 to 4 blocks from the East River, and tthat might have
been waterfront property at the time.)

Remove NOPSAM to email me. Please let
me know if you have posted also.

"Tom Horne, Electrician" wrote:

W Tom
You keep making that statement even though you've been corrected
several times. It is a disservice to the DIY community to
repeatedly say "Water pipe is no longer acceptable as an earth
ground." The US National Electric Code (NEC) requires that any
underground metal water pipe that is ten or more feet in length
shall be used as a grounding electrode. I know that you will now
try to muddy the water by bringing up the requirement for a
supplemental electrode but the fact is that regardless of how
many electrodes you have you must use the underground metal water
pipe as a grounding electrode if it is available on the premise.
You can argue all you want but until the Code Making Panel that
is responsible for chapter 250 of the US NEC changes the code
underground water piping must be used as a grounding electrode
in any locality that has adopted the NEC as that localities code.

w_tom wrote:

You have it backwards, Tom. Previously you made that
claim. Others then noted why you were wrong. Even if a home
is earthed by a water pipe, that water pipe is no longer
sufficient for earthing (exception is legacy conditions). The
code requires bonding to water pipe - grounding for human
safety. The code is quite specific as to what is required for
an earthing electrode.

I don't expect to change Tom Horne's opinion - having
previously quoted code. But for the benefit of others, the
code says in Article 250.53(D)(2):


Supplemntal Electrode Required. A metal underground water
pipe shall be supplemented by an additional electrode of a
type specified in 250.52(A)(2) through (A)(7).


Those six electrodes are 2) Metal Frame of the Building or
Structure, 3) Concrete Encased Electrode (also called Ufer
grounds), 4) Ground Ring (also called Halo ground), 5) Rod and
pipe Electrodes (also called a copper clad ground rod), 6)
Plate Electrodes, or 7) Other Local Metal Underground Systems
or Structures.

If earthed only to a water pipe, then a building does not
have sufficient earthing. If no water pipe exists, any of the
above ground electrodes 2 through 7 are sufficient - need not
be supplemented. The water pipe is no longer sufficient for
earth ground which is why it must be "supplemented". The
Original Poster is advised to install earthing as required by
post 1990 code. This for two reasons - human safety (per
code) and transistor safety (which code does not address).

Building's occupants also want transistor safety.
Therefore a second reason why water pipe earthing is often
insufficient as an earth ground.

The code says water pipe earthing (which was standard before
19909) is insufficient. Appliance protection also demands an
adjacent earthing electrode for other reasons electrical. Two
reasons why water pipe earthing is no longer sufficient. NEC
requires water pipe be bonded to AC electric safety ground -
for human safety reasons. NEC requires other electrodes (2
through 7) for earthing.

Robert11: volts500 also posted a description of other
safety grounds in a post entitled "Grounding Rod Info" in the
newsgroup alt.home.repair on 12 July 2003 at
http://tinyurl.com/hkjq


Quoting only part of the applicable section of the code does you no
credit. I know what your opinion is as do most of the long time
contributers here. What I'm talking about is what the US National
Electric Code requires. While it is true that the code requires interior
metal water piping to be bonded to the neutral of the service it also
requires that any underground metal water piping that is ten or more
feet in length be used as a grounding electrode. The reason that the NEC
requires a supplemental grounding electrode is stated in the handbook
thusly. The portion in brackets & italics is the handbook commentary.
[The requirement to supplement the metal water pipe is based on the
practice of using a plastic pipe for replacement when the original metal
water pipe fails. This type of replacement leaves the system without a
grounding electrode unless a supplementary electrode is provided.] In
other words a driven rod electrode is better than nothing.

Thus it is the risk of later replacement with plastic piping that is the
reason for requiring that the underground metal water piping be
supplemented with another type of grounding electrode. By actual
measurement the underground metal water piping system provides a far
lower resistance to earth than eight or ten foot driven rods.


[Section 250.50 introduces the important concept of a “grounding
electrode system,” in which all electrodes are bonded together, as
illustrated in Exhibit 250.21. Rather than relying totally on a single
electrode to perform its function over the life of the electrical
installation, the NEC encourages the formation of a system of electrodes
“if available on the premises.” There is no doubt that building a system
of electrodes adds a level of reliability and helps ensure system
performance over a long period of time.]
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.
Exception: In industrial and commercial buildings or structures where
conditions of maintenance and supervision ensure that only qualified
persons service the installation, interior metal water piping located
more than 1.52 m (5 ft) from the point of entrance to the building shall
be permitted as a part of the grounding electrode system or as a
conductor to interconnect electrodes that are part of the grounding
electrode system, provided that the entire length, other than short
sections passing perpendicular through walls, floors, or ceilings, of
the interior metal water pipe that is being used for the conductor is
exposed.
(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.
(B) Electrodes Not Permitted for Grounding. The following shall not be
used as grounding electrodes:
(1) Metal underground gas piping system
(2) Aluminum electrodes

--
Tom Horne

Well we aren't no thin blue heroes and yet we aren't no blackguards to.
We're just working men and woman most remarkable like you.

"Thomas D. Horne, FF EMT
Dec 30, 2:46 am show options

Quoting only part of the applicable section of the code does you no
credit. I know what your opinion is as do most of the long time
contributers here. What I'm talking about is what the US National
Electric Code requires. While it is true that the code requires
interior
metal water piping to be bonded to the neutral of the service it also
requires that any underground metal water piping that is ten or more
feet in length be used as a grounding electrode. The reason that the
NEC
requires a supplemental grounding electrode is stated in the handbook
thusly. The portion in brackets & italics is the handbook commentary.
[The requirement to supplement the metal water pipe is based on the
practice of using a plastic pipe for replacement when the original
metal
water pipe fails. This type of replacement leaves the system without a
grounding electrode unless a supplementary electrode is provided"


Excellent job Thomas! This is exactly what I thought the reason was
behind requiring a supplemental ground in addition to a water pipe
ground. And I agree, that W Tom completely misrepresents this. His
statements lead one to believe that there is something wrong from an
electrical and lightning protection standpoint with using a water pipe
ground. It's cear from the NEC that this is simply not true and the
real reason is concern over a metal water pipe later being replaced by
plastic, therby leaving the premise with no ground.

What you have described as a “grounding electrode system” is
the classic single point earth ground proven even in the 1930s
to 'harden' high reliability facilities from electronics
damage. Yes, separate earth grounds must be interconnected
also for human safety reasons. But that is completely
irrelevant to the original poster's question, is completely
irrelevant to what I have posted, AND is what we want when
earthing for transistor safety. So what is your point? Your
definition of a 'grounding electrode system' does not
contradict anything previously posted.

Why are you questioning that a water pipe earthing alone is
not sufficient when NEC says otherwise? Why are you adding
irrelevant information about interconnected earth grounds?
Information that is also irrelevant to the original poster's
question?

Nothing I posted here or in years previous said that buried
water pipes cannot also be earthing electrodes. So why do you
post as if I said just that?

Meanwhile another reason for supplemental grounding (besides
plastic pipe) is plumber protection. Plumber doing work on
HIS pipes should not be concerned about electrical hazards.
Supplemental earthing means a plumber does not, if
disconnecting pipes, create an electrical hazard.

Another reason why a water pipe earth ground is typically
not sufficient is also something beyond NEC agenda: transistor
protection.

Water pipe alone is no longer sufficient for earthing.
Nothing posted by Tom Horne supports his contrarian claims.
Other earth grounds (2) through (7) by themselves are
sufficient for earthing - do not require supplemental
earthing. But a water pipe as the building's only earth
ground is no longer sufficient; for numerous reasons.

Robert11's original question was:
... about houses needing, and the NEC requiring, a ground (or
grounding) rod right outside the house.

Correct. The cold water pipe as earth ground is no longer
sufficient. An earthing electrode dedicated only to a
building's electrical system is also required. AND this
ground must also connect, a short distance, to all incoming
utilities.

Now Tom. If I had said that cold water pipe cannot or need
not be connected to building's ground system, then your last
post would have merit. But that is not what I said - ever.
1) I said that cold water pipe must be bonded to a building's
safety ground system. 2) I said that cold water pipe alone is
no longer sufficient as a building's only earth ground. What
you have quoted from the NEC does not dispute either point.
3) What I also posted describes earthing for essential
functions beyond what code calls for. Again, nothing you have
posted disputes that either. So why do you post what is also
irrelevant to the OP's original question?

"Thomas D. Horne, FF EMT" wrote:
Quoting only part of the applicable section of the code does you no
credit. I know what your opinion is as do most of the long time
contributers here. What I'm talking about is what the US National
Electric Code requires. While it is true that the code requires interior
metal water piping to be bonded to the neutral of the service it also
requires that any underground metal water piping that is ten or more
feet in length be used as a grounding electrode. The reason that the NEC
requires a supplemental grounding electrode is stated in the handbook
thusly. The portion in brackets & italics is the handbook commentary.
[The requirement to supplement the metal water pipe is based on the
practice of using a plastic pipe for replacement when the original metal
water pipe fails. This type of replacement leaves the system without a
grounding electrode unless a supplementary electrode is provided.] In
other words a driven rod electrode is better than nothing.

Thus it is the risk of later replacement with plastic piping that is the
reason for requiring that the underground metal water piping be
supplemented with another type of grounding electrode. By actual
measurement the underground metal water piping system provides a far
lower resistance to earth than eight or ten foot driven rods.

[Section 250.50 introduces the important concept of a “grounding
electrode system,” in which all electrodes are bonded together, as
illustrated in Exhibit 250.21. Rather than relying totally on a single
electrode to perform its function over the life of the electrical
installation, the NEC encourages the formation of a system of electrodes
“if available on the premises.” There is no doubt that building a system
of electrodes adds a level of reliability and helps ensure system
performance over a long period of time.]
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.
Exception: In industrial and commercial buildings or structures where
conditions of maintenance and supervision ensure that only qualified
persons service the installation, interior metal water piping located
more than 1.52 m (5 ft) from the point of entrance to the building shall
be permitted as a part of the grounding electrode system or as a
conductor to interconnect electrodes that are part of the grounding
electrode system, provided that the entire length, other than short
sections passing perpendicular through walls, floors, or ceilings, of
the interior metal water pipe that is being used for the conductor is
exposed.
(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.
(B) Electrodes Not Permitted for Grounding. The following shall not be
used as grounding electrodes:
(1) Metal underground gas piping system
(2) Aluminum electrodes

To the OP: if you are going to post the same message to multiple
newsgroups use crossposting - that way multiple people don't have to
answer the same question and we may see a wider range of answers.

The answer to the original question, as stated by Speedy Jim, Tom and by
others at alt.engineering.electrical is that a water pipe is normally
the best easily obtained ground. As has been stated on both newsgroups,
the only reason a ground rod is required, as supplemental electrode, is
that water pipe may someday be replaced by plastic. For an existing
house (that is, the OP) the NEC did not used to require a ground rod and
does not require adding a ground rod unless replacing the service.
Adding one will not improve the ground system unless the water pipe
turns to plastic.

A water pipe is one of 3 electrodes that must be connected, if present,
as the ground system. A rod is a supplemental eletrode, not one of the 3.

I have seen stated typical ground resistance values of 3 ohms for water
pipe, also 0.1 ohm (remember this is usually an extensive network of
metal below the frost line and likely nearer ground water than a rod).
Ground rods are good, acording to the NEC, if their resistance is below
25 ohms. If not below then drive 2 rods and you don't have to measure -
no reason it couldn't be above 25 ohms. Which do you think is a better
ground? Why do you have to measure the ground resistance only with a
rod? I agree entirely with fellow electrician Tom Horne.

Incidentally the second best electrode for a house is likely a concrete
encased electrode. It can be used alone (no rod) and can be used as the
supplemental electrode for a water pipe. If I was building a house I
would include one. They were studied for 18 years and over that period
had a ground resistance of 2.1 to 4.8 ohms.

w_tom wrote:

What you have described as a “grounding electrode system” is
the classic single point earth ground proven even in the 1930s
to 'harden' high reliability facilities from electronics
damage. Yes, separate earth grounds must be interconnected
also for human safety reasons. But that is completely
irrelevant to the original poster's question, is completely
irrelevant to what I have posted, AND is what we want when
earthing for transistor safety. So what is your point? Your
definition of a 'grounding electrode system' does not
contradict anything previously posted.

Why are you questioning that a water pipe earthing alone is
not sufficient when NEC says otherwise? Why are you adding
irrelevant information about interconnected earth grounds?
Information that is also irrelevant to the original poster's
question?

Nothing I posted here or in years previous said that buried
water pipes cannot also be earthing electrodes. So why do you
post as if I said just that?

Meanwhile another reason for supplemental grounding (besides
plastic pipe) is plumber protection. Plumber doing work on
HIS pipes should not be concerned about electrical hazards.
Supplemental earthing means a plumber does not, if
disconnecting pipes, create an electrical hazard.


Actually I thought plumbers were smart enough to handle this. The
current code is that the connection has to be made within 5 feet of the
entrance.

Another reason why a water pipe earth ground is typically
not sufficient is also something beyond NEC agenda: transistor
protection.


Never explained - why the lowest resistance isn't the best protection.

Water pipe alone is no longer sufficient for earthing.
Nothing posted by Tom Horne supports his contrarian claims.
Other earth grounds (2) through (7) by themselves are
sufficient for earthing - do not require supplemental
earthing. But a water pipe as the building's only earth
ground is no longer sufficient; for numerous reasons.


Numerous reasons - never stated.

Robert11's original question was:

... about houses needing, and the NEC requiring, a ground (or
grounding) rod right outside the house.


Correct. The cold water pipe as earth ground is no longer
sufficient. An earthing electrode dedicated only to a
building's electrical system is also required. AND this
ground must also connect, a short distance, to all incoming
utilities.

Apparently there is a problem with an electrode also being a water pipe?
What might that be?

I agree protector blocks for cable and TV should be immediately adjacent
to the panel so all wiring is clamped to the same ground reference. I
would suggest that is likely more important than the grounding
electrode. But then it would seem like the lowest resistance ground path
would be best.

Now Tom. If I had said that cold water pipe cannot or need
not be connected to building's ground system, then your last
post would have merit. But that is not what I said - ever.
1) I said that cold water pipe must be bonded to a building's
safety ground system. 2) I said that cold water pipe alone is
no longer sufficient as a building's only earth ground. What
you have quoted from the NEC does not dispute either point.
3) What I also posted describes earthing for essential
functions beyond what code calls for. Again, nothing you have
posted disputes that either. So why do you post what is also
irrelevant to the OP's original question?

"Thomas D. Horne, FF EMT" wrote:

Quoting only part of the applicable section of the code does you no
credit. I know what your opinion is as do most of the long time
contributers here. What I'm talking about is what the US National
Electric Code requires. While it is true that the code requires interior
metal water piping to be bonded to the neutral of the service it also
requires that any underground metal water piping that is ten or more
feet in length be used as a grounding electrode. The reason that the NEC
requires a supplemental grounding electrode is stated in the handbook
thusly. The portion in brackets & italics is the handbook commentary.
[The requirement to supplement the metal water pipe is based on the
practice of using a plastic pipe for replacement when the original metal
water pipe fails. This type of replacement leaves the system without a
grounding electrode unless a supplementary electrode is provided.] In
other words a driven rod electrode is better than nothing.

Thus it is the risk of later replacement with plastic piping that is the
reason for requiring that the underground metal water piping be
supplemented with another type of grounding electrode. By actual
measurement the underground metal water piping system provides a far
lower resistance to earth than eight or ten foot driven rods.

[Section 250.50 introduces the important concept of a “grounding
electrode system,” in which all electrodes are bonded together, as
illustrated in Exhibit 250.21. Rather than relying totally on a single
electrode to perform its function over the life of the electrical
installation, the NEC encourages the formation of a system of electrodes
“if available on the premises.” There is no doubt that building a system
of electrodes adds a level of reliability and helps ensure system
performance over a long period of time.]
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.
Exception: In industrial and commercial buildings or structures where
conditions of maintenance and supervision ensure that only qualified
persons service the installation, interior metal water piping located
more than 1.52 m (5 ft) from the point of entrance to the building shall
be permitted as a part of the grounding electrode system or as a
conductor to interconnect electrodes that are part of the grounding
electrode system, provided that the entire length, other than short
sections passing perpendicular through walls, floors, or ceilings, of
the interior metal water pipe that is being used for the conductor is
exposed.
(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.
(B) Electrodes Not Permitted for Grounding. The following shall not be
used as grounding electrodes:
(1) Metal underground gas piping system
(2) Aluminum electrodes

"w_tom" wrote in message
...
What you have described as a "grounding electrode system" is
the classic single point earth ground proven even in the 1930s
to 'harden' high reliability facilities from electronics
damage. Yes, separate earth grounds must be interconnected
also for human safety reasons. But that is completely
irrelevant to the original poster's question, is completely
irrelevant to what I have posted, AND is what we want when
earthing for transistor safety.


What is this "transistor safety" that you keep talking about?

Please explain.

Water pipe makes a good low resistance ground. Human safety
demands a low resistance ground for reasons that include, for
example, neutral wire failure.

Transistor safety uses grounding components for a different
purpose. Transistor safety requires a low impedance ground.
If connecting a bonding wire to a water pipe 50 feet away, the
house has a low resistance ground and a high impedance
ground. High impedance means ineffective transistor
protection. Take this fax machine protection as an example:
http://www.epri-peac.com/tutorials/sol01tut.html

Unfortunately AC electric and phone service enter on two
sides of the house - bad construction practice. If 'pictured'
water pipe is a significantly lower impedance connection, then
a destructive transient will find the building's single point
earth ground via NID (surge protector) and cold water pipe.
But in reality, cold water pipes are typically too long, too
many solder joints, too many sharp bends, etc. To connect to
a common point, an additional wire that is not shown. All
increase impedance so much that a transient will also seek a
destructive path to earth via the fax machine. Incoming on
phone line. Outgoing on AC electric wire. Fax machine
damaged because NID was not earthing via a low impedance earth
ground connection.

This demonstrates but one example of how portable phone base
stations, fax machines, and modems are so easily damaged.
Essential to transistor protection is a connection from each
incoming utility, either through a protector or by direct
hardwire, to a common earth ground connection. Single point
earthing most easily accomplished with a ground rod wired
short (ie. less than 10 feet) to AC electric box. For
transistor safety, all incoming utilities (telephone, cable
TV, satellite disk) must make a less than 10 foot connection
to this common earthing point.

Another problem with using a cold water pipe as an earth
ground connection - code wants each utility to be earthed less
than 20 feet to the common point. Pipes (ie outside faucet)
often are just too far - more than 20 feet - to the common
earth ground point.

Labeled 'arrestor' in that picture, same rules apply to that
a 'whole house' protector. Arrestor must make a short
connection to the single point earthing. 30 feet across the
basement to where cold water pipe enters the building is all
but no earth ground to that 'arrestor' - too much impedance.
An earth ground rod adjacent to a breaker box is also for
transistor safety - a low impedance earthing connection.

A most common source of transistor destructive transients to
things such as computer modems is incoming on AC electric.
Wires highest on poles - AC electric - are more often struck;
not lower cable and phone line. If that 'arrestor' does not
connect AC electric wire to earth ground, then a transient
(again in that picture) goes into fax machine (modem) on L
connection, then destructively out on phone wires to NID and
to earth ground. Above demonstrates why fax machines, modems,
and portable phone bases stations are so often damaged by AC
electric wire transients.

Above is pre-WWII technology now made necessary in dwellings
due to something new - transistors. Transistor protection is
often little understood by some electricians who only
understand NEC requirements. NEC does not require transistor
protection. NEC is for human protection. Transistor
protection is defined by the most critical component in a
protection system: earth ground.

Gfretwell has posted how homes are now being built so as to
provide superior transistor safety in pictures at:
http://members.aol.com/gfretwell/ufer.jpg

Another also demonstrates better earthing. None of this
would be required if city water pipe was sufficient as earth
ground for transistor safety:
http://www.knology.net/~res0958z/

Above was earthing for secondary protection. Also necessary
is earthing for primary protection:
http://www.tvtower.com/fpl.html

Oscar_Lives wrote:
"w_tom" wrote in message
...
What you have described as a "grounding electrode system" is
the classic single point earth ground proven even in the 1930s
to 'harden' high reliability facilities from electronics
damage. Yes, separate earth grounds must be interconnected
also for human safety reasons. But that is completely
irrelevant to the original poster's question, is completely
irrelevant to what I have posted, AND is what we want when
earthing for transistor safety.

What is this "transistor safety" that you keep talking about?

Please explain.

Its called 'legacy'. Changes per code required only if
changing or installing new wiring. Code does not require
homeowner to upgrade earthing to unmodified installations.
Code also does not address transistor safety. A short
connection to a dedicated earth ground is installed also as
part of a transistor safety 'system'. That detailed
elsewhere.

Bud-- does not even quote code to justify his post. Code
now says water pipe ground is insufficient. Any other
earthing electrode in that list (A)(2) through (A)(7) is
sufficient for earthing. If using water pipe for earthing,
then other earth grounds must also be installed because a
water pipe ground is no longer sufficient per 250.52(D)(2).
Code is quite clear. Water pipe is no longer sufficient for
earthing as revised code specifically states. Bud-- does not
quote code.

Other reasons for a dedicated earth ground include plumber
safety during a disconnected water pipe. Code also calls for a
jumper wire across water meter for same reasons. Plumber
should not be threatened by electrical hazards. Plumber
safety - another reason why water pipe earth ground is not
sufficient and must be supplemented.

Water pipe must be bonded to AC electric for human safety
reasons. The only electrical connection acceptable to pipes
are connections that remove electricity. This for many
reasons including future use of plastic pipe and plumber
safety. No longer acceptable to wire electrical devices to
water pipes with intent of making that water pipe a safety
ground. Electric wire connections to water pipes are
permitted only to remove dangerous electric currents from
those pipes.

Why does code also require a second earth ground rod if
earth resistance is too high (25 ohms)? Second rod would not
be necessary if water pipe was sufficient as an earth ground.
But again, water pipe is no longer sufficient as an earth
ground. Water pipe must be supplemented by something that is
sufficient for earthing. Second copper clad rod may be
required because an earth ground rod (or any other electrode
from the list (A)(2) through (A)(7) ) is now the essential
earthing electrode. It supplements making water pipe only a
secondary and insufficient earth ground; as overtly stated in
250.53(D)(2) - quoted previously.

Meanwhile, a homeowner wants this adjacent earth ground also
for impedance reasons. Electricians rarely need understand
impedance. Code only demands low resistance. But for
electronics protection, a homeowner needs a low "impedance"
earth ground, which a water pipe often does not provide. See
a reply to Oscar_lives for details explaining transistor
safety and impedance. Also see that post for an earthing
pictures because water pipe ground is not sufficient.

Bud-- wrote:
To the OP: if you are going to post the same message to multiple
newsgroups use crossposting - that way multiple people don't have to
answer the same question and we may see a wider range of answers.

The answer to the original question, as stated by Speedy Jim, Tom and by
others at alt.engineering.electrical is that a water pipe is normally
the best easily obtained ground. As has been stated on both newsgroups,
the only reason a ground rod is required, as supplemental electrode, is
that water pipe may someday be replaced by plastic. For an existing
house (that is, the OP) the NEC did not used to require a ground rod and
does not require adding a ground rod unless replacing the service.
Adding one will not improve the ground system unless the water pipe
turns to plastic.

A water pipe is one of 3 electrodes that must be connected, if present,
as the ground system. A rod is a supplemental eletrode, not one of the 3.

I have seen stated typical ground resistance values of 3 ohms for water
pipe, also 0.1 ohm (remember this is usually an extensive network of
metal below the frost line and likely nearer ground water than a rod).
Ground rods are good, acording to the NEC, if their resistance is below
25 ohms. If not below then drive 2 rods and you don't have to measure -
no reason it couldn't be above 25 ohms. Which do you think is a better
ground? Why do you have to measure the ground resistance only with a
rod? I agree entirely with fellow electrician Tom Horne.

Incidentally the second best electrode for a house is likely a concrete
encased electrode. It can be used alone (no rod) and can be used as the
supplemental electrode for a water pipe. If I was building a house I
would include one. They were studied for 18 years and over that period
had a ground resistance of 2.1 to 4.8 ohms.

w_tom wrote:

Water pipe makes a good low resistance ground. Human safety
demands a low resistance ground for reasons that include, for
example, neutral wire failure.

Transistor safety uses grounding components for a different
purpose. Transistor safety requires a low impedance ground.
If connecting a bonding wire to a water pipe 50 feet away, the
house has a low resistance ground and a high impedance
ground. High impedance means ineffective transistor
protection. Take this fax machine protection as an example:
http://www.epri-peac.com/tutorials/sol01tut.html

As I said protector blocks for cable and TV should be immediately
adjacent to the panel so all wiring is clamped to the same ground
reference. You don't explain how a ground rod would help in this
instance. Adding a ground rod near the FAX is not going to provide a low
impedance to keep the ground reference for the FAX the same as the
incoming neutral.

For
transistor safety, all incoming utilities (telephone, cable
TV, satellite disk) must make a less than 10 foot connection
to this common earthing point.

Incoming utilities listed have to have protector blocks near the power
panel to get a common grounding reference.

How does a 10 foot wire to a high resistance ground rod provide a lower
ground impedance than a grounding electrode conductor and water pipe?
This is cental to your arguments. Perhaps you could explain and also
provide some citations that support your view.

For a 500A service the conductor to a ground rod has to be #6. The
conductor to a water pipe has to be 2/0 - 3.5 x the area. How come?
Surges include high frequency components for which impedance is
important. Grounding electrode conductor and water pipe has one function
of limiting surges.

Another problem with using a cold water pipe as an earth
ground connection - code wants each utility to be earthed less
than 20 feet to the common point.

Cite the code.


A most common source of transistor destructive transients to
things such as computer modems is incoming on AC electric.
Wires highest on poles - AC electric - are more often struck;
not lower cable and phone line. If that 'arrestor' does not
connect AC electric wire to earth ground, then a transient
(again in that picture) goes into fax machine (modem) on L
connection, then destructively out on phone wires to NID and
to earth ground. Above demonstrates why fax machines, modems,
and portable phone bases stations are so often damaged by AC
electric wire transients.

Clamping all incoming wires to the same the same ground reference is the
best way I know to protect electronics. That requires the protector
blocks to be near the electrical panel. (More properly thay have to be
near each other.) That is likely a lot more important than resistance or
impedance to ground. If all wiring was clamped to the same reference
with no ground connection could electronics see a difference.

Gfretwell has posted how homes are now being built so as to
provide superior transistor safety in pictures at:
http://members.aol.com/gfretwell/ufer.jpg

This is a concrete encased electrode which I said is probably the second
best electrode (after water pipes). It is one of 3 electrodes that must
be included in a ground system, if present. (The other 2 are water pipe
and building steel, which a home doesn't have.) Not included: ground rod.

Another also demonstrates better earthing. None of this
would be required if city water pipe was sufficient as earth
ground for transistor safety:
http://www.knology.net/~res0958z/

Most of us don't put 55 foot high lightning rods in our back yard. Not
particualrly relevant.

-------------
With regard to: Bud-- does not even quote code to justify his post. You
do not understand why water pipes are required to have a SUPPLEMENTAL
electrode and don't listen to people who do understand. Since arguing
the code is pointles, I tried Physics - ground resistance. That doesn't
seem to work either.

bud--

Mercy! I'm not quite sure what you're trying to say here, or
what the point of some of the irrelevant URLs/comments might be,
but ... either you need to step back and put your heard around
this again, or seek further education and experience.
You'll probably object to my post here, but it's so typical of
many on this group lately that I just can't hold it in any
longer. Those who have nothing to say, should say exactly that.
Those who do have something to say, should be clear and concise
about it. Rationalization and guessing have no place in the
realm of safety.

"w_tom" wrote in message
...
: Water pipe makes a good low resistance ground. Human safety
: demands a low resistance ground for reasons that include, for
: example, neutral wire failure.

=== Water pipe does not make a "low resistance" ground. It
makes a "ground", period. The word "low" must have a contextual
reference to be meaningful and there is none there. Besides,
it's not resistive; it also contains a reactive component,
sometimes surprisingly large.
:
: Transistor safety uses grounding components for a different
: purpose.
=== What is "transistor safety"? That makes no sense. You
apparently mean protection, as in protecting semi-conductor
devices from overvoltages. Further, you will find nearly no
transistors used anywhere these days in current designs.
Semiconductor, yes; transistor type semiconductors; pretty scarce
these days.

.... Transistor safety requires a low impedance ground.
=== No, it requires a stable reference w/r to the rest of the
ckt.

: If connecting a bonding wire to a water pipe 50 feet away, the
: house has a low resistance ground and a high impedance
: ground.
=== Resistance or impedance? Are you using these
interchangably? They are two entirely different things.
Impedance would be the term you need here as the reactive
components are substantial.

High impedance means ineffective transistor
: protection.
=== Now you've switched from safety to protection. Which is it?
What high impedance are you talking about?

Take this fax machine protection as an example:
: http://www.epri-peac.com/tutorials/sol01tut.html
:
: Unfortunately AC electric and phone service enter on two
: sides of the house - bad construction practice.
=== Bad assumption: that's a schematic representation, not a
bad construction practice, and the only thing you can discern
from it is the marked distances indicated for wiring.

If 'pictured'
: water pipe is a significantly lower impedance connection, then
: a destructive transient will find the building's single point
: earth ground via NID (surge protector)
=== NID is NOT a surge protector. NID is the Network Interface
Device, and PART of it is surge suppression, NOT for any purpose
other than protecting the demarcation point connections at a 600V
clamping voltage. YOu've mis-assumed some things there.

and cold water pipe.
: But in reality, cold water pipes are typically too long, too
: many solder joints, too many sharp bends, etc.
=== Sharp BENDS matter to resistance/impedance? I don't THINK
so! What are you worried about, the kinetic energy of the moving
electrons going around a corner where centifugal force slows them
down? I hope not!
You don't understand conductivity, I'm afraid. You're just
parroting and trying to justify something with rationalization.
It doesn't work.

To connect to
: a common point, an additional wire that is not shown.

All
: increase impedance so much that a transient will also seek a
: destructive path to earth via the fax machine.
=== A "transient" will NOT seek a "destructive" path to earth.
It will seek the path of least resistance to current flow whether
that consist of pure resistance (it doesn't) or either of the
reactive elements. Another way to state it is, it will seek any
potential lower than itself in magnitude. That includes ac
characteristics, by the way.

Incoming on
: phone line. Outgoing on AC electric wire. Fax machine
: damaged because NID was not earthing via a low impedance earth
: ground connection.
=== NO ELECTRONICS are protected, nor are they intended to be
protected by, the telco surge suppression components, which are
often arc-over devices or gas tubes or carbon stacks.
:
: This demonstrates but one example of how portable phone base
: stations, fax machines, and modems are so easily damaged.
=== It does indeed, but it does so because there is no
protection afforded to, nor intended to be afforded to,
electronic equipment by the telco protectors. You've completely
lost track of what a ground reference means in these contexts.
Or, don't know what it means.

: Essential to transistor protection is a connection from each
: incoming utility, either through a protector or by direct
: hardwire, to a common earth ground connection. Single point
: earthing most easily accomplished with a ground rod wired
: short (ie. less than 10 feet) to AC electric box. For
: transistor safety, all incoming utilities (telephone, cable
: TV, satellite disk) must make a less than 10 foot connection
: to this common earthing point.
=== It's obvious you've been reading, but ... you're not putting
things together correctly.
:
....
: A most common source of transistor destructive transients to
: things such as computer modems is incoming on AC electric.
: Wires highest on poles - AC electric - are more often struck;
: not lower cable and phone line. If that 'arrestor' does not
: connect AC electric wire to earth ground, then a transient
: (again in that picture) goes into fax machine (modem) on L
: connection, then destructively out on phone wires to NID and
: to earth ground. Above demonstrates why fax machines, modems,
: and portable phone bases stations are so often damaged by AC
: electric wire transients.
=== Wow, those are some huge assumptions and incorrect at that.
That come nowhere close to explaining why fax machines etx. are
so often damaged by electric wire transients. In reality, if you
research for facts just a little bit, you'll find that most
telephone appliances are damaged by transients because they have
NO protection, or under rated protection.
Lightning is NOT the overwhelming reason for damage to those
components. Lightning is one of the least controllable damage
elements in existance. You can only partially protect against
small, almost tiny lightning hits.
Most transients are generated from other sources, the majority
of them being inductive loads, grid controlling elements in the
ac plants, transformer problems, and even the loads and motors
within a building itself.

I don't object to someone trying to help things out; I do object
to obvious rationalizations and attempts to justify things to
one's own "feelings" of how something should be. The world just
isn't'' like that.
:
: Above is pre-WWII technology now made necessary in dwellings
: due to something new - transistors. Transistor protection is
: often little understood by some electricians who only
: understand NEC requirements.
=== NEC requirements have NO, nada, zero, consideration for the
protection of semiconductor devices and thus is of no concern to
"some electricians". I do think though that you're on shaky
ground by saying they have no understanding - many actually do.

NEC does not require transistor
: protection. NEC is for human protection. Transistor
: protection is defined by the most critical component in a
: protection system: earth ground.
=== Oh, gosh, no. Earth ground has almost nothing to do with
the actual protection. It's the RELATIVE electrical position of
the references, whether it be a dc voltage, 0 volts, or even a
high voltage, that matters. I can run a 3 Volt microprocessor on
a 100V DC line if the other side of the line stays within 97
volts (or 103 as the case may be) of whichever is determined
(chosen) to be the reference. Yes, 100V DC CAN be considered
GROUND to a ckt and everything will work fine, including
component protection against transients. Actually, you could
look at some TV schematics to get an idea of how some of that
works.

:
: Gfretwell has posted how homes are now being built so as to
: provide superior transistor safety in pictures at:
: http://members.aol.com/gfretwell/ufer.jpg
:
: Another also demonstrates better earthing. None of this
: would be required if city water pipe was sufficient as earth
: ground for transistor safety:
: http://www.knology.net/~res0958z/
=== Noo, that's NOT the reason water pipes aren't allowed as
ground any longer. Actually, transistors being as old as they
are, they were quite well protected by cold water pipes and the
same standard surge protection used by many people today. That
changed when it was no longer allowable to use water pipes for a
safety earth, and as I've tried to indicate, it is almost a moot
point to anything.
You will still find many thousands of homes with water pipe
grounds, with modern electonic equipment that works very well and
just as well as any other system you can imagine.

:
: Above was earthing for secondary protection. Also necessary
: is earthing for primary protection:
: http://www.tvtower.com/fpl.html
=== I don't think you have any idea what primary and secondary
mean here, do you?

Enough soap boxing, I guess. I don't have anything else to say
on the matter, so that is what I'm going to say.

The simple answer: Water pipe is no longer sufficient as a
building's earth ground. Post 1990 code requires other
earthing electrode selected from the list in paragraphs
(A)(2) through (A)(7) so that building earthing is sufficient
and minimally acceptable.

To reply to 'mixed within' inline replies: Yes, many homes
have only water pipes for earthing. Eventually, all that will
be corrected as we slowly upgrade to minimally acceptable
ground standards. Many homes also have two prong wall
receptacles. Is that acceptable today? Of course not. That
also is slowly being corrected.

Meanwhile for both human safety and for something new to
homes (transistor safety), water pipe earthing is no long
sufficient. Homeowner is encouraged to upgrade building
earthing for more than human safety reasons.

Transistor? Show me any IC that does not have transistors?
Furthermore, transistors - discrete parts - are widely used in
most every electronic device. I am responding here to
something that Pop should have obviously known by looking at
the PC board even on a disk drive. He also ignores
unnecessary transistor damage from decades previous. A
solution that begins with sufficient earthing.

No, I have not used resistance and impedance
interchangeably. Mercy! Read what was posted carefully to
appreciate specific references to each. Comprehending
impedance is necessary appreciate electrical concepts in that
fax machine example; why so much unnecessary transistor damage
has occurred for so many decades.

NID contains protection that was once only an arc over
device - gas discharge tube or GDT. Appreciate why earthing
is essential for phone circuits - why GDTs work. If one
thinks any protector blocks or absorbs destructive transients,
then one never learned what effective protection does. NID
does provide effective transistor protection - but only as
good as its earth ground. Where does the human start to
eliminate transistor damage? Earth ground as even
demonstrated in that previous www.tvtower.com citation.

BTW your 600 volt number is an obsolete 1950s standard that
was once 400 to 600 volts. Times and protectors have changed.

I make no assumptions or rationalizations having learned
this stuff decades ago as an engineer and from experience. It
is routine to protect from direct lightning strikes as even
addressed by Bodle and Gresh in their Mar 1961 paper in the
Bell System Technical Journal. And yes, they are discussing
'transistor' protection back then. Their paper even
demonstrates why underground utility wires require properly
earthed service entrance protection.

There was no rationalization. You are apparently having
difficulty even with concepts of impedance verses resistance.
Those who are not familiar also might post:
Oh, gosh, no. Earth ground has almost nothing to do with
the actual protection.
Earthing is THE one essential component that literally every
building protection system requires. Pop: Read highly
regarded application notes from Polyphaser. Does Polyphaser
discuss their product line? Of course not. Polyphaser
discusses THE most critical component in protection - earth
ground:
http://www.polyphaser.com/ppc_ptd_home.aspx

Many science papers dating back even to the 1930s define
effective protection as based upon techniques pioneered by Ben
Franklin in 1752. Was Franklin also rationalizing? Were GE
and Westinghouse researchers rationalizing when their
equipment atop the Empire State Building could suffer about 25
direct strikes annually without damage? What was posted is
well proven science. But many today still remain in denial.
In denial even about what the NEC now demands for earthing a
building only for human safety.

Water pipe earth ground is no longer sufficient as a
building's only earth ground. This also for so many reasons
provided in previous posts. This proven by literally quoting
NEC text. And yet still many will deny what the NEC itself
demands. Water pipe earth ground is no longer sufficient to
earth a building.

Above is about transistor safety. Different from what the
Original Poster asks and what NEC addresses with demands for
supplemental earthing. A water pipe earth ground is no longer
sufficient. Pop, looking forward to questions once you have
learned from Polyphaser's app notes. Yes, those wires atop
telephone poles are little different from radio station
antenna. As the Polyphaser app notes will demonstrate,
underground wires are also at risk. All three connect
directly to transistors inside a building. Transistor
protection is only as effective as its earth ground.

Pop wrote:
Mercy! I'm not quite sure what you're trying to say here, or
what the point of some of the irrelevant URLs/comments might be,
but ... either you need to step back and put your heard around
this again, or seek further education and experience.
You'll probably object to my post here, but it's so typical of
many on this group lately that I just can't hold it in any
longer. Those who have nothing to say, should say exactly that.
Those who do have something to say, should be clear and concise
about it. Rationalization and guessing have no place in the
realm of safety.

An example demonstrates the earthing problem. A 12 AWG wire
from wall receptacle maybe 50 feet back to mains box has less
than 0.2 ohms resistance. That same wire would have something
like 120 ohms impedance. Lets say a tiny 100 amp transient
seeks earth ground via that 50 foot wire. Therefore a wall
receptacle - and adjacent electronics - will be at something
less than 12,000 volts. Will that transient seek earth via
that safety ground wire? Of course not. It will also seek
other and destructive paths via adjacent electronics.

Wire length is but one reason why a wall receptacle safety
ground is not sufficient as earth ground. Also explains why
plug-in protectors are so ineffective.

Essential to minimizing wire impedance are wire length, no
sharp bends, and other characteristics cited previously. Also
important is a concept cited by Bud--
Clamping all incoming wires to the same the same ground
reference is the best way I know to protect electronics. ...
The quality of a service entrance protector is only as
effective as its earth ground which is why distance to that
earthing is so critical and why single point earthing is
essential. That means the 6 AWG wire does not go up over a
foundation and then down to an earth ground rod. That wire
goes through foundation somewhere just above the ground rod so
that wire distance is shorter with sharp bends eliminated.
Also important is that earthing wire remain separated from
other non-earthing wires to avoid induced transients.

Yes, lower resistance does help which is why high
reliability facilities such as electric substations expand
their earth ground to also lower resistance. It is also why
earthing should be planned when the footing are poured.
Equipotential being another aspect of superior earthing.

Unfortunately we still don't build as if the transistor
exists. We still do earthing as an afterthought. Effective
earthing addresses concepts in excess of that performed by
conventional household earthing. Equipotential being a
concept of transistor protection that is not as essential to
human protection. If we built buildings for effective
transistor protection, then Ufer grounds would be routine; and
not some afterthought to supplement water pipe ground such as
ground rods. Even water pipe would enter a building adjacent
to all other utilities to contribute to transistor safety.

Even NEC requires all incoming electrical utilities be
earthed to a common point for human safety - a problem still
found even in some new homes.

That 20 foot requirement from NEC is article 800.40(A)(4):
Length. The primary protector grounding conductor shall
be as short as practicable. In one- and two-family
dwellings, the primary protector grounding conducutor
shall be as short as practicable, not to exceed 6.0
meters (20 ft) in length.

Same paragraphs is also found in Article 820.

Cinergy demonstrates how to solve earthing problems created
when utilities arrive at wrong locations. A problem often
created by service installers or builders who still have not
learned about proper earthing:
http://www.cinergy.com/surge/ttip08.htm

Concrete encased grounding (Ufer grounds) were so well
proven even before WWII as to even protect munitions from
direct lightning strikes. If water pipe earthing was so
effective, then why do they implement Ufer grounding even in
buildings with water pipe grounds? Halo grounds are but
another way of improved earthing.

Again, to answer the original poster's question - water pipe
earthing alone is no longer sufficient to meet code. Upgrade
to accomplish more than just meet code. Transistor protection
is only as effective as a building's earth ground.

Bud-- wrote:
As I said protector blocks for cable and TV should be immediately
adjacent to the panel so all wiring is clamped to the same ground
reference. You don't explain how a ground rod would help in this
instance. Adding a ground rod near the FAX is not going to provide
a low impedance to keep the ground reference for the FAX the same
as the incoming neutral.
...

Incoming utilities listed have to have protector blocks near the power
panel to get a common grounding reference.

How does a 10 foot wire to a high resistance ground rod provide a lower
ground impedance than a grounding electrode conductor and water pipe?
This is cental to your arguments. Perhaps you could explain and also
provide some citations that support your view.

For a 500A service the conductor to a ground rod has to be #6. The
conductor to a water pipe has to be 2/0 - 3.5 x the area. How come?
Surges include high frequency components for which impedance is
important. Grounding electrode conductor and water pipe has one
function of limiting surges.

Another problem with using a cold water pipe as an earth
ground connection - code wants each utility to be earthed less
than 20 feet to the common point.

Cite the code.
...

Clamping all incoming wires to the same the same ground reference
is the best way I know to protect electronics. That requires the
protector blocks to be near the electrical panel. (More properly
thay have to be near each other.) That is likely a lot more
important than resistance or impedance to ground. If all wiring
was clamped to the same reference with no ground connection could
electronics see a difference.

Gfretwell has posted how homes are now being built so as to
provide superior transistor safety in pictures at:
http://members.aol.com/gfretwell/ufer.jpg

This is a concrete encased electrode which I said is probably the second
best electrode (after water pipes). It is one of 3 electrodes that must
be included in a ground system, if present. (The other 2 are water pipe
and building steel, which a home doesn't have.) Not included: ground rod.

Another also demonstrates better earthing. None of this
would be required if city water pipe was sufficient as earth
ground for transistor safety:
http://www.knology.net/~res0958z/

Most of us don't put 55 foot high lightning rods in our back yard. Not
particualrly relevant.

-------------
With regard to: Bud-- does not even quote code to justify his post. You
do not understand why water pipes are required to have a SUPPLEMENTAL
electrode and don't listen to people who do understand. Since arguing
the code is pointles, I tried Physics - ground resistance. That doesn't
seem to work either.

bud--

w_tom wrote:
An example demonstrates the earthing problem. A 12 AWG wire
from wall receptacle maybe 50 feet back to mains box has less
than 0.2 ohms resistance. That same wire would have something
like 120 ohms impedance. Lets say a tiny 100 amp transient
seeks earth ground via that 50 foot wire. Therefore a wall
receptacle - and adjacent electronics - will be at something
less than 12,000 volts. Will that transient seek earth via
that safety ground wire? Of course not. It will also seek
other and destructive paths via adjacent electronics.

Wire length is but one reason why a wall receptacle safety
ground is not sufficient as earth ground. Also explains why
plug-in protectors are so ineffective.

I never talked about branch ckts and don't want to start now. If I did I
would want a citation for 120 ohms.
Impedance of ground rod and water pipe would be relevant.

Concrete encased grounding (Ufer grounds) were so well
proven even before WWII as to even protect munitions from
direct lightning strikes. If water pipe earthing was so
effective, then why do they implement Ufer grounding even in
buildings with water pipe grounds?

Perhaps because a supplementary ground is required for a water pipe
because it may be replaced by plastic and ground rods are way worse than
either. Not obvious who "they" are. If it is gfretwell, in a current
thread he says the gound conductivity near him is very bad. Sounds like
the Ufer is a foundation ring. An unrelated video tape shows driving a
10' rod in Florida with a water table about 3' down, connecting 120V and
getting a current of about 1.5A (implies 80 ohms ground resistance).

Halo grounds are but
another way of improved earthing.

Probably mean ground ring in NEC. Phaser uses halo (in the air) and it
isn't what you want.

-----------
I actually only planned to respond to your citations in response to me
and pop:

Cinergy demonstrates how to solve earthing problems created
when utilities arrive at wrong locations. A problem often
created by service installers or builders who still have not
learned about proper earthing:
http://www.cinergy.com/surge/ttip08.htm

Cinergy in effect talks about a common ground reference which I have
emphasized several times. We probably substantialy, but not entirely
agree on this. Nothing on water pipes and ground rods which we don't
agree on.

Where does the human start to
eliminate transistor damage? Earth ground as even
demonstrated in that previous www.tvtower.com citation.

I have no idea what at that site is relevant

Polyphaser
discusses THE most critical component in protection - earth
ground:
http://www.polyphaser.com/ppc_ptd_home.aspx

The most consistent protection in the papers is having a common ground
reference for power and signal. They talk about using ground rods only
to ground towers - which constitute large lightning rods. No one
protects their house from direct lightning strikes unless they install
lightning rods/air terminals. Most of the info is specific to lightning,
towers and antenna coax - not particularly relevant to grounding
elsewhere. If you are going to cite it you should pick out the relevant
papers, if any.

bud--

That's a grand collection of misquotes and minsinformation and
hooey references that are irrelevant to most anything here.
Like I said before, I'm not inclined to continue to debate these
OT side trips of useless misinformation. If you'd like to have a
sensible, detailed debate, start a new thread where it belongs.
People are beginning to complain about responses that have
nothing to do with the OP's questions, and I have to agree it
does make it hard to find a meaningful response if there is one.



"w_tom" wrote in message
...
: The simple answer: Water pipe is no longer sufficient as a
: building's earth ground. Post 1990 code requires other
: earthing electrode selected from the list in paragraphs
: (A)(2) through (A)(7) so that building earthing is sufficient
: and minimally acceptable.
:
: To reply to 'mixed within' inline replies: Yes, many homes
: have only water pipes for earthing. Eventually, all that will
: be corrected as we slowly upgrade to minimally acceptable
: ground standards. Many homes also have two prong wall
: receptacles. Is that acceptable today? Of course not. That
: also is slowly being corrected.
:
: Meanwhile for both human safety and for something new to
: homes (transistor safety), water pipe earthing is no long
: sufficient. Homeowner is encouraged to upgrade building
: earthing for more than human safety reasons.
:
: Transistor? Show me any IC that does not have transistors?
: Furthermore, transistors - discrete parts - are widely used in
: most every electronic device. I am responding here to
: something that Pop should have obviously known by looking at
: the PC board even on a disk drive. He also ignores
: unnecessary transistor damage from decades previous. A
: solution that begins with sufficient earthing.
:
: No, I have not used resistance and impedance
: interchangeably. Mercy! Read what was posted carefully to
: appreciate specific references to each. Comprehending
: impedance is necessary appreciate electrical concepts in that
: fax machine example; why so much unnecessary transistor damage
: has occurred for so many decades.
:
: NID contains protection that was once only an arc over
: device - gas discharge tube or GDT. Appreciate why earthing
: is essential for phone circuits - why GDTs work. If one
: thinks any protector blocks or absorbs destructive transients,
: then one never learned what effective protection does. NID
: does provide effective transistor protection - but only as
: good as its earth ground. Where does the human start to
: eliminate transistor damage? Earth ground as even
: demonstrated in that previous www.tvtower.com citation.
:
: BTW your 600 volt number is an obsolete 1950s standard that
: was once 400 to 600 volts. Times and protectors have changed.
:
: I make no assumptions or rationalizations having learned
: this stuff decades ago as an engineer and from experience. It
: is routine to protect from direct lightning strikes as even
: addressed by Bodle and Gresh in their Mar 1961 paper in the
: Bell System Technical Journal. And yes, they are discussing
: 'transistor' protection back then. Their paper even
: demonstrates why underground utility wires require properly
: earthed service entrance protection.
:
: There was no rationalization. You are apparently having
: difficulty even with concepts of impedance verses resistance.
: Those who are not familiar also might post:
: Oh, gosh, no. Earth ground has almost nothing to do with
: the actual protection.
: Earthing is THE one essential component that literally every
: building protection system requires. Pop: Read highly
: regarded application notes from Polyphaser. Does Polyphaser
: discuss their product line? Of course not. Polyphaser
: discusses THE most critical component in protection - earth
: ground:
: http://www.polyphaser.com/ppc_ptd_home.aspx
:
: Many science papers dating back even to the 1930s define
: effective protection as based upon techniques pioneered by Ben
: Franklin in 1752. Was Franklin also rationalizing? Were GE
: and Westinghouse researchers rationalizing when their
: equipment atop the Empire State Building could suffer about 25
: direct strikes annually without damage? What was posted is
: well proven science. But many today still remain in denial.
: In denial even about what the NEC now demands for earthing a
: building only for human safety.
:
: Water pipe earth ground is no longer sufficient as a
: building's only earth ground. This also for so many reasons
: provided in previous posts. This proven by literally quoting
: NEC text. And yet still many will deny what the NEC itself
: demands. Water pipe earth ground is no longer sufficient to
: earth a building.
:
: Above is about transistor safety. Different from what the
: Original Poster asks and what NEC addresses with demands for
: supplemental earthing. A water pipe earth ground is no longer
: sufficient. Pop, looking forward to questions once you have
: learned from Polyphaser's app notes. Yes, those wires atop
: telephone poles are little different from radio station
: antenna. As the Polyphaser app notes will demonstrate,
: underground wires are also at risk. All three connect
: directly to transistors inside a building. Transistor
: protection is only as effective as its earth ground.
:
: Pop wrote:
: Mercy! I'm not quite sure what you're trying to say here, or
: what the point of some of the irrelevant URLs/comments might
be,
: but ... either you need to step back and put your heard
around
: this again, or seek further education and experience.
: You'll probably object to my post here, but it's so
typical of
: many on this group lately that I just can't hold it in any
: longer. Those who have nothing to say, should say exactly
that.
: Those who do have something to say, should be clear and
concise
: about it. Rationalization and guessing have no place in the
: realm of safety.

"w_tom" wrote in message
...
: An example demonstrates the earthing problem. A 12 AWG wire
: from wall receptacle maybe 50 feet back to mains box has less
: than 0.2 ohms resistance.

That same wire would have something
: like 120 ohms impedance.
At what frequency, and what are the approx reactive components?
See, this is the kind of non-information I'm talking about.

Lets say a tiny 100 amp transient
: seeks earth ground via that 50 foot wire. Therefore a wall
: receptacle - and adjacent electronics - will be at something
: less than 12,000 volts.
Time? Duration? Energy? What is the power in each component?
Think about it.

Will that transient seek earth via
: that safety ground wire? Of course not. It will also seek
: other and destructive paths via adjacent electronics.
No, ALL freqs/rise/falls will not seek the same path. Think
about it.
:
: Wire length is but one reason why a wall receptacle safety
: ground is not sufficient as earth ground. Also explains why
: plug-in protectors are so ineffective.
I don't recall anyone saying that was the case. Did they?
:
: Essential to minimizing wire impedance are wire length, no
: sharp bends,
My gosh, what are you doing, applying field theory and
waveguides? This is exactly what makes your possibly well
intentioned information so useless. I'm surprised you left out
the skin effect and a few other nice nouns you could have dropped
in there.

and other characteristics cited previously. Also
: important is a concept cited by Bud--
: Clamping all incoming wires to the same the same ground
: reference is the best way I know to protect electronics. ...
Where did anyone claim it wasn't? The "best" wasn't the
question; sufficient or acceptable were the words, IIRC.

: The quality of a service entrance protector is only as
: effective as its earth ground which is why distance to that
: earthing is so critical and why single point earthing is
: essential. That means the 6 AWG wire does not go up over a
: foundation and then down to an earth ground rod. That wire
: goes through foundation somewhere just above the ground rod so
: that wire distance is shorter with sharp bends eliminated.

Uhh, the sharp bends problem isn't for impedance or electrical
considerations; it's physical properties related. Think about
what you're saying.

: Also important is that earthing wire remain separated from
: other non-earthing wires to avoid induced transients.
I don't think that was any part of the subject; true but not
directly relevant.
:
: Yes, lower resistance does help which is why high
: reliability facilities such as electric substations expand
: their earth ground to also lower resistance. It is also why
: earthing should be planned when the footing are poured.
: Equipotential being another aspect of superior earthing.
Superior earthing: What's that go to do with anything?
Completely irrelevant to the subject matter.
:
: Unfortunately we still don't build as if the transistor
: exists. We still do earthing as an afterthought. Effective
: earthing addresses concepts in excess of that performed by
: conventional household earthing. Equipotential being a
: concept of transistor protection that is not as essential to
: human protection. If we built buildings for effective
: transistor protection, then Ufer grounds would be routine; and
: not some afterthought to supplement water pipe ground such as
: ground rods. Even water pipe would enter a building adjacent
: to all other utilities to contribute to transistor safety.
More irrelevance; no point to the entire para.
:
: Even NEC requires all incoming electrical utilities be
: earthed to a common point for human safety - a problem still
: found even in some new homes.
"Even NEC"?

....
More attempts at double-speak and name dropping clipped.
:
: Again, to answer the original poster's question - water pipe
: earthing alone is no longer sufficient to meet code. Upgrade
: to accomplish more than just meet code. Transistor protection
: is only as effective as a building's earth ground.

To take your bent for a moment, a "transistor" is defined as an
e-b-c junction with physical leads attached. Semiconductor
technology does indeed use the concept of transistors within
chips et al for analogic discussion, but they are not transistors
unless, like you, a person wished to take the word apart into its
components, and work from there.
It's also possible, still in your realm of fuzziness, to build
a computer system with NO earth reference, but with controlled
references, which will operate perfectly. I used to use such a
system daily in my routine daily work for many years.
And BTW, resistance IS a component of Impedance. If you wish
to use the terms interchangeably, you need to add the words pure
and reactance to your talk.

Don't be a blatherskite.
:
: Bud-- wrote:
: As I said protector blocks for cable and TV should be
immediately
: adjacent to the panel so all wiring is clamped to the same
ground
: reference. You don't explain how a ground rod would help in
this
: instance. Adding a ground rod near the FAX is not going to
provide
: a low impedance to keep the ground reference for the FAX the
same
: as the incoming neutral.
: ...
:
: Incoming utilities listed have to have protector blocks near
the power
: panel to get a common grounding reference.
:
: How does a 10 foot wire to a high resistance ground rod
provide a lower
: ground impedance than a grounding electrode conductor and
water pipe?
: This is cental to your arguments. Perhaps you could explain
and also
: provide some citations that support your view.
:
: For a 500A service the conductor to a ground rod has to be
#6. The
: conductor to a water pipe has to be 2/0 - 3.5 x the area. How
come?
: Surges include high frequency components for which impedance
is
: important. Grounding electrode conductor and water pipe has
one
: function of limiting surges.
:
: Another problem with using a cold water pipe as an earth
: ground connection - code wants each utility to be earthed
less
: than 20 feet to the common point.
:
: Cite the code.
: ...
:
: Clamping all incoming wires to the same the same ground
reference
: is the best way I know to protect electronics. That requires
the
: protector blocks to be near the electrical panel. (More
properly
: thay have to be near each other.) That is likely a lot more
: important than resistance or impedance to ground. If all
wiring
: was clamped to the same reference with no ground connection
could
: electronics see a difference.
:
: Gfretwell has posted how homes are now being built so
as to
: provide superior transistor safety in pictures at:
: http://members.aol.com/gfretwell/ufer.jpg
:
: This is a concrete encased electrode which I said is probably
the second
: best electrode (after water pipes). It is one of 3 electrodes
that must
: be included in a ground system, if present. (The other 2 are
water pipe
: and building steel, which a home doesn't have.) Not included:
ground rod.
:
: Another also demonstrates better earthing. None of this
: would be required if city water pipe was sufficient as
earth
: ground for transistor safety:
: http://www.knology.net/~res0958z/
:
: Most of us don't put 55 foot high lightning rods in our back
yard. Not
: particualrly relevant.
:
: -------------
: With regard to: Bud-- does not even quote code to justify his
post. You
: do not understand why water pipes are required to have a
SUPPLEMENTAL
: electrode and don't listen to people who do understand. Since
arguing
: the code is pointles, I tried Physics - ground resistance.
That doesn't
: seem to work either.
:
: bud--

In article , w_tom
wrote:

...
Why does code also require a second earth ground rod if
earth resistance is too high (25 ohms)? Second rod would not
be necessary if water pipe was sufficient as an earth ground.
But again, water pipe is no longer sufficient as an earth
ground. Water pipe must be supplemented by something that is
sufficient for earthing. Second copper clad rod may be
required because an earth ground rod (or any other electrode
from the list (A)(2) through (A)(7) ) is now the essential
earthing electrode. It supplements making water pipe only a
secondary and insufficient earth ground; as overtly stated in
250.53(D)(2) - quoted previously.
...

Not sure how wise it is to add to this discussion, but...

You may want to consult a qualified commentary book on the NEC for
better explanations. One that I found extremely helpful is Practical
Electrical Wiring, 18th Edition (2002 NEC) by Richter and Hartwell.
It's been around awhile, the latest author Hartwell is a master
electrician and Code Panel member, and I think this book has been
endorsed numerous times in this conference.

It explains (Chapter 16: Installing Service Entrances and Grounds):
"In a large city with cast iron water mains and everyone connected
through copper water laterals, the total resistance to ground from any
given connection [on your water pipe] may be less than 1 ohm, about as
good as possible." It goes on to say that the reason for requiring
supplementary electrodes (per NEC 250.53 as you quote) is due to
possible future replacement of water supply pipe with plastic or
insertion of dielectric unions. If that has not taken place, the pipe
is by far the best grounding electrode the average house can hope for.
This correlates with what the electricians in this newsgroup have been
stating.

I have an older house with no supplementary electrode, but will be
installing one (probably with 3 or 4 rods) to comply with Code when I
upgrade my service. But with a 3/4" copper supply pipe entering my
basement, buried about 10' deep for the 30' straight run to the main
line in the street, and countless miles of deeply buried main water
lines connected to that... How could a couple of 5/8" diameter, 8' long
rods in my yard ever compete with that? If a lightning-induced surge
came down my wires after I installed the rods, I'd have to wonder if
more than even a few percent of the amps would choose to drain out in
the sand and clay around those grounding rods instead of into the water
main network.

If that supply pipe were replaced with plastic, then yes, the grounding
rods would become vital, and that's why (in my understanding) they are
required by NEC 250.53(D) as preemptive protection against that change.

Hey Pop. You remember what transistors are? They are
things you said are not inside electronics today. Transistors
- those things found inside integrated circuits no longer
exist? That is my point. You argue without a technical grasp
of reality - including a claim that transistors are no longer
used. The code is quite specific. That water pipe earth
ground is not longer sufficient to earth a building.

The only misinformation is the 'missing information' posted
by Pop. He does not comprehend quoted that he then insults.
One day Pop will make a claim supported by facts and numbers.
Not today. He still insists there are no transistor inside
integrated circuits.

Pop wrote:
That's a grand collection of misquotes and minsinformation and
hooey references that are irrelevant to most anything here.
Like I said before, I'm not inclined to continue to debate these
OT side trips of useless misinformation. If you'd like to have a
sensible, detailed debate, start a new thread where it belongs.
People are beginning to complain about responses that have
nothing to do with the OP's questions, and I have to agree it
does make it hard to find a meaningful response if there is one.

Provided was an example of wire impedance (it was not a
discussion of branch circuits); which explains WHY each earth
ground connection must be short, no splices, no sharp bends,
not inside metallic conduit, etc. Wire has impedance which
is why short wire length is critical to earthing for
transistor protection.

To repeat what was posted: Cinergy also demonstrates
solutions to bad construction - where the utilities don't
enter at a common location. The need for single point
earthing is good for human safety but essential to transistor
safety.

Above is about earthing for the secondary protection
'system'. www.tvtower.com demonstrates earthing of the
primary protection 'system'. Layered protection 'systems'.
Each layer of protection is defined by its single point earth
ground. http://www.tvtower.com/fpl.html also demonstrates
another earth ground that contributes to transistor
protection.

Polyphaser discusses protecting incoming wires from
lightning. If your house is not adjacent to a 50 foot radio
tower, then a 'tower' that lightning seeks is your house or
those utility poles that connect directly to household
transistors. Earthing that applies to protecting radio towers
also applies to home protection. To lightning, that tower and
those incoming house wires are same.

But then Polyphaser - an industry benchmark - discusses more
that just radio towers. What does Polyphaser discuss? Their
products? Of course not. Polyphaser discusses earthing - the
most critical component also in a home protection system.
What is discussed here? Earthing the house - for same reasons
that Polyphaser describes in:
http://www.polyphaser.com/ppc_ptd_home.aspx

Same principle that were once standard in places that had
electronics - radio stations and telephone switching stations
- are now necessary in other buildings that also have
electronics - the home.

Why extensive earthing of those FL homes?
http://members.aol.com/gfretwell/ufer.jpg
Again, water pipe earth ground alone just is not sufficient.
Not sufficient to meet code AND not sufficient to protect
household transistors.

Bud-- wrote:
w_tom wrote:
I never talked about branch ckts and don't want to start now. If
I did I would want a citation for 120 ohms.
Impedance of ground rod and water pipe would be relevant.
...

Perhaps because a supplementary ground is required for a water pipe
because it may be replaced by plastic and ground rods are way worse than
either. Not obvious who "they" are. If it is gfretwell, in a current
thread he says the gound conductivity near him is very bad. Sounds like
the Ufer is a foundation ring. An unrelated video tape shows driving a
10' rod in Florida with a water table about 3' down, connecting 120V and
getting a current of about 1.5A (implies 80 ohms ground resistance).
...

Probably mean ground ring in NEC. Phaser uses halo (in the air) and it
isn't what you want.

-----------
I actually only planned to respond to your citations in response to me
and pop:
...

Cinergy in effect talks about a common ground reference which I have
emphasized several times. We probably substantialy, but not entirely
agree on this. Nothing on water pipes and ground rods which we don't
agree on.

Where does the human start to
eliminate transistor damage? Earth ground as even
demonstrated in that previous www.tvtower.com citation.

I have no idea what at that site is relevant

Polyphaser
discusses THE most critical component in protection - earth
ground:
http://www.polyphaser.com/ppc_ptd_home.aspx

The most consistent protection in the papers is having a common ground
reference for power and signal. They talk about using ground rods only
to ground towers - which constitute large lightning rods. No one
protects their house from direct lightning strikes unless they install
lightning rods/air terminals. Most of the info is specific to lightning,
towers and antenna coax - not particularly relevant to grounding
elsewhere. If you are going to cite it you should pick out the relevant
papers, if any.

bud--

Reasons provided for the supplementary electrode - plastic
pipe, etc - are what most agree on. What some
non-electricians are having a problem with are other
electrical and electronic reasons why a water pipe ground is
not sufficient. Involves parameters that concern engineers -
that include and go beyond an electrician's code
requirements. Remember, code is only about human safety. But
the earthing system also performs other functions - such as
transistor safety.

One reason why a water pipe ground is not sufficient - it
does not belong to the electrical system and therefore can be
compromised: plumber disconnects a pipe that is electrically
hot, plumber installs plastic pipe, etc. All these reasons
provided previously are not in dispute (except where one only
wants to argue).

Your reasoning only assumes resistance. Grasped the concept
of impedance. Resistance of ground rods at signficantly less
than 25 ohms is sufficient for transistor protection. So if
you lower resistance to 2 ohms, have you improve things by 10
times? Of course not. 2 ohms is only a minor improvement -
provides a marginal improvement. Lowering resistance provides
an exponentially decreasing advantage. But impedance, as
discussed elsewhere, is a major bottleneck to transistor
safety.

If water pipe ground was so good, then why do high
reliability facilities that only used copper water pipes still
install Ufer, wire mesh, and other grounds as demonstrated in:
http://members.aol.com/gfretwell/ufer.jpg
The water pipe ground with all that lower resistance is still
not sufficient for earthing. Again, if looking at resistance,
then other aspects of earthing, summarized in previous posts,
are being ignnored. Notice why those posts are so long.
Notice the so many application notes about earthing for laymen
at:
http://www.polyphaser.com/ppc_ptd_home.aspx
There is more to earthing than just low resistance. If you
only want to meet code, then only worry only about
resistance. But reasons why others don't rely on a water pipe
ground are found in electrical concepts such as impedance and
equipotential. These are parameters that electricians need
not learn, are not part of the human safety code, and have
been made important by household transistors.

The code says water pipe must be supplemented for things
such as plastic pipe and plumber safety. But facilities that
had transistors decades ago supplemented that water pipe
ground for electrical reasons that will never be part of human
safety code (NEC). Those same reasons for better earthing
(such as halo or Ufer grounds) are now in your house.

chocolatemalt wrote:
Not sure how wise it is to add to this discussion, but...

You may want to consult a qualified commentary book on the NEC for
better explanations. One that I found extremely helpful is Practical
Electrical Wiring, 18th Edition (2002 NEC) by Richter and Hartwell.
It's been around awhile, the latest author Hartwell is a master
electrician and Code Panel member, and I think this book has been
endorsed numerous times in this conference.

It explains (Chapter 16: Installing Service Entrances and Grounds):
"In a large city with cast iron water mains and everyone connected
through copper water laterals, the total resistance to ground from any
given connection [on your water pipe] may be less than 1 ohm, about as
good as possible." It goes on to say that the reason for requiring
supplementary electrodes (per NEC 250.53 as you quote) is due to
possible future replacement of water supply pipe with plastic or
insertion of dielectric unions. If that has not taken place, the pipe
is by far the best grounding electrode the average house can hope for.
This correlates with what the electricians in this newsgroup have been
stating.

I have an older house with no supplementary electrode, but will be
installing one (probably with 3 or 4 rods) to comply with Code when I
upgrade my service. But with a 3/4" copper supply pipe entering my
basement, buried about 10' deep for the 30' straight run to the main
line in the street, and countless miles of deeply buried main water
lines connected to that... How could a couple of 5/8" diameter, 8' long
rods in my yard ever compete with that? If a lightning-induced surge
came down my wires after I installed the rods, I'd have to wonder if
more than even a few percent of the amps would choose to drain out in
the sand and clay around those grounding rods instead of into the water
main network.

If that supply pipe were replaced with plastic, then yes, the grounding
rods would become vital, and that's why (in my understanding) they are
required by NEC 250.53(D) as preemptive protection against that change.

Hmm, , you're pretty closed minded and ignorant. When you can't
confuse someone with rationalization disguised as facts you get
"interesting". I suspected a troll early on - too bad I and
others bothered to feed you.

Not sure how wise it is to add to this discussion, but...

Might have been the best post in the thread.

bud--