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Thread: Encountering cut panel ground wires

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    Radon Contractor and Water Treatment 99k's Avatar
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    Default Encountering cut panel ground wires

    This is the second time this month where I went to install a water system and found the #4 ground wire from the panel to the copper water distribution line was purposely cut at the grounding clamp. Why would anyone want to do such a thing? In both instances, I noticed a lot of communications equipment in these mechanical areas ... is the issue possibly interference?

  2. #2

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    If I were to hazard a guess that #4 to the plumbing was the old building ground. A new good grounding source was most likely created when the telcom/computer equipment was installed and the old cut at the clamp to stop any possible loops.

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    Quote Originally Posted by renaissanceEE View Post
    If I were to hazard a guess that #4 to the plumbing was the old building ground. A new good grounding source was most likely created when the telcom/computer equipment was installed and the old cut at the clamp to stop any possible loops.
    In both cases, these homes were less than 10 years old. They appear to have had the proper grounds outside and the electrical panels were not upgraded. It would seem cutting a ground is going against code ... I thought it should be to two grounding rods and to the water line.
    Please explain what you mean by creating a "loop"?

  4. #4

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    loops is short for ground loops.
    Having a good common ground source is is high importance when you have expensive electronics talking to each other over copper from distant ends of a building. You don't want that ground wire in twisted pair the shield in coax to be a different ground potentials at either end, it will shorten the life of the interface and cause on going problems.
    When engineering telecom upgrades for the military it was standard practice even for a two room building to replace the building ground if the current was unknown or of low quality such as plumbing.

    That being said this being a home "a lot of communications equipment in these mechanical areas" is mostly likely home electronics which were not installed by a telecom professional, so things like equipment life and reliability were not taken into account, and honestly not a major issue.

    I would say your cut wire at ground clips to the plumbing was not related to the communication equipment.
    Last edited by renaissanceEE; 10-01-2008 at 11:20 AM.

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    Electrician Chris75's Avatar
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    Quote Originally Posted by renaissanceEE View Post
    If I were to hazard a guess that #4 to the plumbing was the old building ground. A new good grounding source was most likely created when the telcom/computer equipment was installed and the old cut at the clamp to stop any possible loops.
    How on earth would a bonded metal pipe cause a ground loop? The only thing I see causing a loop is having the tel/catv grounding not bonded to the electrical grounding system.


    To answer the OP's question, Probably a plumber that really didnt understand the function of the wire to begin with.
    Are these city water supplies or well water in your area?

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    Electrician Chris75's Avatar
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    Quote Originally Posted by renaissanceEE View Post
    A new good grounding source was most likely created when the telcom/computer equipment was installed and the old cut at the clamp to stop any possible loops.
    That would be a code violation, ALL grounding electrodes must be USED if present, and the water system would still need to be bonded even if not used as an electrode.

  7. #7

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    I read somewhere that an electric company refused to connect the electric service if there was a cold water pipe ground. They would only connect the electric service with ground rod(s) being used as the service ground.

    Perhaps this is a "new" trend to no longer use cold water pipe grounds?

    I could see why this would be and that is the high cost of copper/metal and people replacing main underground water pipes with plastic, then there goes your ground. And if it is not this way now, then will likely be that way in the future (will replace with plastic).

    I would suggest you document that the ground was disconnected before you did any work and it was not you who disconnected the ground. (CYA) Send copy to customer.

  8. #8
    Moderator & Master Plumber hj's Avatar
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    Default ground

    IN this area the water system must be grounded if it is metallic, AND also the gas system if there is one.

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    Retired Defense Industry Engineer jadnashua's Avatar
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    In the desert, and in some types of soils, it is very hard to establish any decent ground so the more places you can attach and the larger the surface area contact you have, the better it will be.

    While in the army in the desert, to make good grounds for communications, they'd pour salt then water down the ground around the ground stakes, otherwise, it was tough to establish decent communications and maintain safety.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  10. #10

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    The way the electrician got around the electric company was to run a ground from the water pipe to one of the ground rods (not to panel). Then the electric company was happy.

    This would avoid the situation of an energized water pipe system if underground pipe was replaced with plastic, the ground was lost to the ground rods from the panel, and there was a loose neutral.

  11. #11

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    P.S. I agree all metal water pipes *should* be grounded.

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    Radon Contractor and Water Treatment 99k's Avatar
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    Are these city water supplies or well water in your area?
    In both instances the water supply was well water. In both instances the home was new enough that these appeared to be the original well tanks and so I don't think the plumber cut these grounds.

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    Quote Originally Posted by Billy_Bob View Post
    I read somewhere that an electric company refused to connect the electric service if there was a cold water pipe ground. They would only connect the electric service with ground rod(s) being used as the service ground.

    Perhaps this is a "new" trend to no longer use cold water pipe grounds?

    I could see why this would be and that is the high cost of copper/metal and people replacing main underground water pipes with plastic, then there goes your ground. And if it is not this way now, then will likely be that way in the future (will replace with plastic).

    I would suggest you document that the ground was disconnected before you did any work and it was not you who disconnected the ground. (CYA) Send copy to customer.
    As far as I'm aware, copper (or metal) pipes should be grounded regardless of whether the incoming line from a well (usually 1" poly) or is city water (typically 3/4" min. copper). In this last house I verified the grounding rods where present outside and reconnected the ground at the water line.

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    Electrician Chris75's Avatar
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    Its this simple, we (electricians) must bond the water piping system and all available grounding electrodes. Its really not hard to understand, if the water system leaves the house with 10' or more in metal underground piping, then it must be used as an electrode.

  15. #15

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    Quote Originally Posted by jadnashua View Post
    In the desert, and in some types of soils, it is very hard to establish any decent ground so the more places you can attach and the larger the surface area contact you have, the better it will be.

    While in the army in the desert, to make good grounds for communications, they'd pour salt then water down the ground around the ground stakes, otherwise, it was tough to establish decent communications and maintain safety.
    I saw this done at a mountain top satellite/microwave station. Very rocky up there, 5 ground rods driven and interconnected, plus a saltwater drip system from a couple of 50 gallon drums. They would have to cart water up there every so often to keep the drip lines going (and would add salt).

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