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Thread: Grounding cold water pipe

  1. #1

    Default Grounding cold water pipe

    Hello,

    I live on an acreage in Saskatchewan, Canada, and recently had an electrical contractor out to provide buried service to the house. Because our house is about 30 years old, he also spent a bit of time bringing things up to code, apparently a requirement.
    One of the improvements he did was run a ground wire from the breaker box to the cold water pipe. Now, I understand why this is done in the city, where the cold water pipe is inherently grounded – but in my case, I have an internal cistern/pump arrangement and none of the pipes extend outside the house, consequently they are NOT providing any sort of ground point. When I brought this fact to the electrician’s attention, he insisted that it was still the right thing to do. Since then, I have talked to several electricians and they’re all rather vague on this issue.
    The way I see it, in my situation, that ground wire is more of a potential hazard than a safeguard. I haven’t disconnected it yet, but I really think I should – if anything goes wrong, my water pipes would become electrically “hot”. As it stands, it does about as much good as if I ran it to my metal stair railing.

    Thanks for your help on this,

    Regards,

    Dave

  2. #2
    Licensed Electrical Contractor Speedy Petey's Avatar
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    Quote Originally Posted by DaveU View Post
    The way I see it, in my situation, that ground wire is more of a potential hazard than a safeguard. I haven’t disconnected it yet, but I really think I should – if anything goes wrong, my water pipes would become electrically “hot”.
    Absolutely the opposite.
    If anything goes wrong and the pipes become energized the breaker will now trip because your piping system is BONDED to the electrical system's grounded neutral. Without this BOND the pipes would STAY energized.

    A "ground" as in the sense of a ground rod or water pipe electrode is NOT a safety ground. At lease not in the sense of a ground that will trip a circuit breaker.
    Meaning if you sink a ground rod outside and hook it up to an ungrounded receptacle, and there is a short to ground, the breaker will NOT trip. It will simply send current into the ground and bring up worms at best and kill someone at worst.
    The "safety" ground in your house is the neutral bond in the main panel.

  3. #3
    Plumber jimbo's Avatar
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    What you say makes some sense. Don't know if you are correct or the electrician is correct, since I am not at all familiar with your cistern system. I believe the Canadian Electrical Code will be the final answer. Hopefully, your electrician based his work on that. You could check with the inspectors or code officials in the city to confirm.

  4. #4

    Question

    Quote Originally Posted by Speedy Petey View Post
    Absolutely the opposite.
    If anything goes wrong and the pipes become energized the breaker will now trip because your piping system is BONDED to the electrical system's grounded neutral. Without this BOND the pipes would STAY energized.
    Thanks for your reply. Why would my pipes ever become enegized?

    regards,

    Dave

  5. #5

    Smile

    Quote Originally Posted by jimbo View Post
    What you say makes some sense. Don't know if you are correct or the electrician is correct, since I am not at all familiar with your cistern system. I believe the Canadian Electrical Code will be the final answer. Hopefully, your electrician based his work on that. You could check with the inspectors or code officials in the city to confirm.
    This is the next step for me. I've posted this question in a couple of forums, and the replies I received are pretty much a 50/50 split as to whether this is a good thing or not.

    Thank you,

    regards,

    Dave

  6. #6
    In the Trades Bob NH's Avatar
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    The US NEC requires bonding of major metal systems so that if they are accidently energized by a fault current that current will be safely dissipated.

    An example of possible accidental energizing would be if an element of an electric water heater, or one of the conductors or controls, were to become accidently in contact with the metal parts of the water heater.

    V. Bonding
    250.90 General. Bonding shall be provided where necessary to ensure electrical continuity and the capacity to conduct safely any fault current likely to be imposed.

    250.104 (A) Metal Water Piping. The metal water piping system shall be bonded as required in (A)(1), . . .

    250.104 (A)(1) General. Metal water piping system(s) installed in or attached to a building or structure shall be bonded to the service equipment enclosure, the grounded conductor at the service, the grounding electrode conductor where of sufficient size, or to the one or more grounding electrodes used. . . .

  7. #7
    Electrical Contractor/Instructor jwelectric's Avatar
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    Bob

    It is the International NEC not just the US NEC

    In 250.104 there is a subsection that addresses the element of a water heater

    (B) Other Metal Piping. Where installed in or attached to a building or structure, metal piping system(s), including gas piping, that is likely to become energized shall be bonded to the service equipment enclosure, the grounded conductor at the service, the grounding electrode conductor where of sufficient size, or to the one or more grounding electrodes used. The bonding jumper(s) shall be sized in accordance with 250.122, using the rating of the circuit that is likely to energize the piping system(s). The equipment grounding conductor for the circuit that is likely to energize the piping shall be permitted to serve as the bonding means. The points of attachment of the bonding jumper(s) shall be accessible.


    The requirement found in (A) has to do with past code cycles. I order to have this requirement changed someone will have to come up with a reason for the change. With a lot of the big cities such as New York and Chicago and various others that still have underground metal water pipes it is easy to see why the requirement found in 250.104(A) remains.

    With these underground metal water pipes in place it is possible to have the interior metal water pipes become energized from another source other than the service or branch circuits of the building in which the requirement to bond originates.

  8. #8

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    Why would my pipes ever become enegized?

    Trust us, it happens.

    There are appliances that hook to both water and power. A fault could occur there.

    There are cables laying on pipes.

    There are cases where a neutral (return path of a circuit) gets broken and the water pipe become the conductor. I have personally see that twice.


    Do NOT remove it.

  9. #9
    DIY Senior Member BrianJohn's Avatar
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    Listen I seldom tout my speciailities, but I am a power quality consultant with in which a large portion of my business is grounding, grounding issues and solving grounding issues. BELIEVE ME anyone telling you NOT TO GROUND, is WRONG and in this case you (our your family) could be dead and that's wrong no matter how you cut it.

  10. #10

    Smile Grounding cold water pipe

    Hello,

    OK, I've been looking at this from the wrong end, I think I've "got it" now. I was always under the assumtion that cold water pipe connection was merely to supply an alternate ground - now that I understand it's real purpose, and what can go wrong, I'll certainly leave it in place.

    Thanks a lot to everyone for your explanations and suggestions.

    regards,

    Dave

  11. #11

    Default

    Ah....you're no fun.

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