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Grounding metal piping rehash Terry 07-26-2007
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Posted by bud-- on August 1, 2007, 12:42 pm
w_tom wrote:
>> I have never seen a source that says an external buried wire between
>> phone NID and CATV entry and power service 'ground' will keep the
>> 'ground' potential the same at all three - the basis of a "single point
>> ground". A ground rod is also required at the CATV entry.
>
> Bud routinely forgets to see things that would expose his plug-in
> protector as ineffective.

My post, was about earthing, not plug-in suppressors.

>
> Earthing must accomplish two task - equipotential and conductivity.
> To achieve equipotential beneath a building, then all earthing must be
> 'single point'. Some facilities only use an earth ground rod. Some
> install earthing as demonstrated in
> http://www.cinergy.com/surge/ttip08.htm

Repeats what w_ previously posted without explaining how the external
wire provides a “single point ground” - as challenged in the quote at
the top.

>
> Others use far more serious earthing just to achieve a little better
> earth ground (ie Ufer grounds). Some examples from those who want
> effective protection rather than expensive 'magic boxes':
> http://www.psihq.com/iread/ufergrnd.htm
> http://scott-inc.com/html/ufer.htm
> http://members.aol.com/gfretwell/ufer.jpg

In the US, Ufer (concrete encased electrode) grounds are required for
new construction with footings or foundations. They are actually a good
grounding electrode. Far better that ground rods.

Terry could install a Ufer ground. All he would have to do is tear out
about 20 feet of his basement wall and footing and reinstall it. Is
that what you are suggesting.

And nobody is talking about a “magic box”. Since you insist on dragging
in plug–in suppressors, the IEEE guide says that if you do not have a
single point ground "the only effective way of protecting the equipment
is to use a multiport protector."

>
> Curious how they understood a well proven technology that Bud has
> never heard of.

If w_ was not a troll he would admit Ufer grounds have been in many of
my posts.

> They are installing protection. Bud is promoting
> grossly overpriced plug-in protectors that have no dedicated earthing.

The troll’s favorite topic again.

For reliable information on surges and surge protection see the IEEE
guide at:
http://omegaps.com/Lightning%20Guide_FINALpublishedversion_May051.pdf
Or the NIST guide at:
http://www.nist.gov/public_affairs/practiceguides/surgesfnl.pdf

The IEEE guide explains plug-in suppressors work by CLAMPING the voltage
on all wires (signal and power) to the common ground at the suppressor.
Plug-in suppressors do not work primarily by earthing The guide
explains earthing occurs elsewhere. (Read the guide starting pdf page 40).

Both guides say plug-in suppressors are effective.

w_ has never found a link that says plug-in suppressors are not effective.

--
bud--

Electric Radiant Heat 468x60
Posted by bud-- on July 29, 2007, 5:23 pm
w_tom wrote:
>> Well this is still my question. What if some of the piping gets
>> replaced with PVC? It happens all the time. I see no reason to have
>> to rely on the copper in the basement as a grounding path. The CATV
>> should be bonded to the service mast.

Ask the cable company to move the ground to the mast. Make sure your
electric service is grounded - may require adding 2 ground rods. Make
sure the water pipes are bonded.



For reliable information on surges and surge protection see the IEEE at:
http://omegaps.com/Lightning%20Guide_FINALpublishedversion_May051.pdf
Or the NIST guide at:
http://www.nist.gov/public_affairs/practiceguides/surgesfnl.pdf

>
> A point about code changes in the past 40 years: pipes installed by
> a plumber should not achieve electrical code grounding requirements.
> Electrical code wants its own earthing and wants its own dedicated
> bonding. Meanwhile, electrical code still demands that piping be
> bonded - so that pipes do not become energized and become human safety
> problems.

The NEC requires now, as it has required for a very long time, that a
metal underground water service pipe, 10 feet or longer underground, be
used as a grounding electrode for an electrical service. Bonding can use
a little different methods and is required when the service pipe is less
than 10 foot metal underground.

>
> How could NICs and router be damaged? A similar example. Lightning
> struck AC electric. Surge protectors adjacent to two computers simply
> connected that surge from black 'hot' wire to many other wires into
> each powered off computer. Surge was shunted from black wire to green
> wire and through network card on two computers. Surge traveled via
> network into a third computer's NIC card. Through motherboard ground,
> out modem, and to earth via phone line. Semiconductors in network
> cards and modem replaced to restore entire system AND to trace that
> surge.

When used as shown in the IEEE and NIST guides, and manufacturers
literature, plug-in surge suppressors protect connected equipment.
Protected equipment is all connected to the same suppressor or external
wires, including phone, CATV, go through the suppressor.


> A surge must
> be earthed before it can even enter the building so that protection
> inside all electronics is not overwhelmed.

Both guides recognize earthing, single point ground, service panel
suppressors and plug-in suppressors.
If you don’t have a single point ground a service panel suppressor does
not always protect.

> Most
> important - each incoming wire must make a dedicated connection of
> 'less than 10 feet' to the same earthing electrode. How those
> connections are installed is as critical as electrode resistance -
> short, no bends, no splices, separated from all other non-earthing
> wires, all earthing wires are independent until all meet at the
> earthing electrode, etc.

The point of a “single point ground” is that ground wires from phone,
CATV, ... protectors connect with short wires to the earthing wire at
the power service. If there is a strong surge the ‘ground’ at the house
will lift from ‘absolute’ ground. The whole point is that the ‘grounds’
for the power, phone, CATV, ... lift together. Francois Martzloff, who
wrote the NIST guide, has written "the impedance of the grounding system
to 'true earth' is far less important than the integrity of the bonding
of the various parts of the grounding system."


> A summary was posted in comp.sys.mac.comm on
> 4 Jul 2007 entitled "DSL speed" at
> http://tinyurl.com/2gbgef

While you are at it, read the responses.

>
> Pipes are traditionally poor earthing connections.

Urban metal underground water supply systems have very low resistances
to ground. More limited systems are likely to be a lot better than
ground rods, the likely electrode that Terry will use. A “good” ground
rod for the NEC is a 25 ohms to ground – very poor. Usually 2 rods are
used and the resistance doesn’t have to be measured.

Starting with the 2005 NEC a Ufer ground/concrete encased electrode is
also required for new construction with concrete foundations. Ufer is
also a good ground and makes a good “supplemental” electrode.

Connection to metal water pipes has for quite a while been required to
be within 5 feet of the entrance to the building.

> CATV must make a short connection to same
> electrode that all other utilities also make that short connection to.

The short connection is to the earthing wire at the power service.

> Grounding to pipes (not to be confused with bonding) is not acceptable
> as it was 40 years ago.

The only change has been the requirement to add a “supplemental”
electrode in the case that the metal water service pipe was replaced by
plastic, as happened to Terry.


As is well known to some on this newsgroup, w_ has some bizarre ideas.

--
bud--

Posted by Terry on July 29, 2007, 5:25 pm
wrote:

>
>Ask the cable company to move the ground to the mast. Make sure your
>electric service is grounded - may require adding 2 ground rods. Make
>sure the water pipes are bonded.
>
>
Thanks.
Great info

Posted by Art Todesco on July 27, 2007, 2:42 pm
Terry wrote:
> The thing I am pondering now it that I have a dead modem, dead router,
> and 2 dead motherboards.
>
> I would like to be able to pin it on the CATV guys as it almost had to
> come in on the CATV as I have a UPS and both computer power supplies
> are good. The only thing that was not connected to the surge
> suppressor were the Cat 5s going to the network cards. That was an
> over site on my part as the UPS does have network jacks.
>
> I agree with you that the piping "should" be grounded. I want to know
> if it "has" to be grounded.
>
> I think it was you that posted a link to the NEC online once. Do you
> still have that link? I saved the link, but the computer is not
> working at the moment. :)
>
> As always, thanks for you suggestions.
>
> On Thu, 26 Jul 2007 19:43:16 -0400, "RBM" <rbm2(remove
> this)@optonline.net> wrote:
>
>> Your internal copper water pipe, except small isolated sections, should be
>> bonded to the grounding electrode system, which in your case is going to be
>> one or two driven ground rods connected to the neutral/ground bar of your
>> main service panel.
>>
>> The CATV guys will ground their equipment to anything they can find that's
>> grounded
>>
>>
>>> To remove dangerous voltage on metal parts from a ground fault,
>>> electrically conductive metal water piping systems, metal sprinkler
>>> piping, metal gas piping, and other metal piping systems, as well as
>>> exposed structural steel members """""""that are likely to become
>>> energized"""""""", must be bonded to an effective ground-fault current
>>> path [250.4(A)(4)]. Although bonding isn't required for isolated
>>> sections of metal water piping connected to a nonmetallic water piping
>>> system, metal water piping systems must be bonded in accordance with
>>> the following:
>>>
>>> My house is about 40 years old. I just took a hit on my computer
>>> equipment. I think it is because the CATV is bonded to my cold water
>>> pipe. I don't think the copper pipe is grounded.
>>>
>>> My water heater is gas so it is unlikely to become energized. Is the
>>> copper pipe in my basement required to be grounded?
>>>
>>> Can I make the CATV guys ground their equipment to my service mast as
>>> my grounding electrode is likely buried on an inside wall that is
>>> covered with sheet rock and a concrete floor?

I had almost the same blowup; the cable
modem, router and motherboard .... plus
my scanner got it too. My cable was
grounded at the NE corner of the building
to a ground rod, which the cable company
put in many years ago. The current
thinking is to ground the cable to the
electric meter. My electric meter is at
the
other end of the building wrapped around
by a deck. So, I called Comcast
and ask that they come out to properly
ground my cable service. Before they
came, I pulled up a few key boards on
the decking and added a couple of pull
wires from the area of the electric
meter, to the outside edges of the deck.
When
the tech came, he said, "well, I was
going to tell you that I'd have to
reschedule,
due to the large amount of work, but you
did it all, so I'll do it!" They ran a new
drop to the pedestal, added a cable box
next to the electric meter and ground
it all to the electric meter. LOL,
shortly after I canceled my cable modem as
fast DSL was available and, in a few
weeks I will be canceling Comcast in favor
of Dish.

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