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Grounding metal piping rehash Terry 07-26-2007
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Posted by Terry on July 26, 2007, 6:06 pm
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?




Posted by RBM on July 26, 2007, 7:43 pm
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?
>
>
>



Posted by Terry on July 26, 2007, 8:19 pm
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?
>>
>>
>>
>

Posted by RBM on July 26, 2007, 9:01 pm
Here ya go:
http://nfpa-acs-01.gvpi.net:8080/rrserver/browser?title=/NFPASTD/7005SB



> 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?
>>>
>>>
>>>
>>



Posted by bud-- on July 27, 2007, 12:02 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.
>

Originally your water pipe was required to be used as a grounding
electrode and connected to the power system ground. That connection now
has to be within 5' of the entrance of the water pipe to the house. Your
house is old enough the connection could have been anywhere.

With the PVC water service you now have, the interior metal water pipe
has to be bonded to the electrical system ground with similar rules, but
the connection no longer has to be within 5' of the entrance. Bonding
requirements are in 250.104-A.

If the water pipe is not connected to the power system ground it is not
the CATV guy’s problem.

---------
The requirements for grounding electrode for CATV are in 820.100-B.
(They are about the same for phone.)

The only point on water pipe that can be used for the CATV ground is the
first 5 feet inside the house. (This may have been different in the past.)

Your metal electric service mast is another permissible grounding point.

(In recent versions of the code, there has to be an accessible point
provided to connect the CATV, phone, ... ground to.)

The grounding conductor from the CATV entry block has to be 20' or less,
(or a ground rod has to be added and the CATV block still has to connect
to the power grounding system). But the connection from the CATV entry
block to the earthing wire at the power service should be as short as
possible as I said under single point ground in your previous thread.

---------
You don’t describe your computer setup. If you have widely separated
computers, each connected to its own suppressor, and interconnected by
ethernet, a surge can shift the ground potential at one end resulting in
a high voltage between computer and ethernet cable at both ends.

As I said in your previous thread, when using a plug-in suppressor all
interconnected equipment needs to be connected to the same plug-in
suppressor, or interconnecting wires need to go through the suppressor.
And external connections, like ethernet, phone, CATV also need to go
through the suppressor . Connecting all wiring through the suppressor
prevents damaging voltages between power and signal wires. A UPS can act
as a plug-in suppressor.

If *all* equipment was connected to the same suppressor, the ethernet
cables wouldn’t have to go through the UPS.

Another question is what are the surge protection ratings of the
suppressor/UPS.

--
bud--

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