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Thread: Live Broken Wire Underground

  1. #1
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    Live Broken Wire Underground

    Would like to know if a energized wire is cut underground like UF wire feeding some exterior lights and the lights are off could you still see amp draw with an amp meter due to leakage in the ground or would you see no current flow?

  2. #2
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    It would depend on the conditions of the soil. In very dry sand it would be doubtful, in wet salted (fertilized for example) soil it would be possible.

    Roger
    Moderator

  3. #3
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    How much current would depend highly on the soil conditions. However there would be some current no matter what. Whether your meter could measure it or not is a different story.
    Bob

  4. #4
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    Theoretically, all else being equal, you get more current if both the grounded and ungrounded conductors are cut in the same location and in contact with the soil. Then you just have a short path through the earth from one to the other, with less resistance. If only the ungrounded conductor is cut, and the return path is a much longer distance through the earth to a grounding electrode(s), you'd get much less current.

    The conditions of the soil/earth are still paramount.

  5. #5
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    We see faults in sandy soil where the sand has turn to glass. At some point the current was high enough to accomplish that. That does not happen often, so the answer is, depends.
    Tom
    TBLO

  6. #6
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    Quote Originally Posted by ptonsparky View Post
    We see faults in sandy soil where the sand has turn to glass. At some point the current was high enough to accomplish that. That does not happen often, so the answer is, depends.
    I see that sometimes as well. Almost never on 120 volt applications - unless maybe if lightning was a factor.

  7. #7
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    As current flows through soil around some of those faults, it dries up that soil making it a higher resistance which results in less current.

    I once had a open circuit in an underground conductor and had a lot of trouble locating it. It was sandy soil and conditions had been very dry at the time. Dug two different holes in what I thought were most likely places for a fault to be according to my locator yet found nothing wrong in those spots. Ended up setting up sprinkler over the area and came back a few hours later - found the right spot very quickly. The locator finds where return current is leaking from the conductor via earth, soil was so dry there wasn't enough return current to get a good locate.

  8. #8
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    Quote Originally Posted by kwired View Post
    As current flows through soil around some of those faults, it dries up that soil making it a higher resistance which results in less current.

    I once had a open circuit in an underground conductor and had a lot of trouble locating it. It was sandy soil and conditions had been very dry at the time. Dug two different holes in what I thought were most likely places for a fault to be according to my locator yet found nothing wrong in those spots. Ended up setting up sprinkler over the area and came back a few hours later - found the right spot very quickly. The locator finds where return current is leaking from the conductor via earth, soil was so dry there wasn't enough return current to get a good locate.
    What were you using as a locator? Just curious.

  9. #9
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    Quote Originally Posted by jaggedben View Post
    What were you using as a locator? Just curious.
    Not sure what model number is, but same manufacturer and very similar to this one, but probably about 30 years old. I didn't think I would find one on their site that looked so similar to what I have after that many years.

    What I have does not have the passive mode abilities that that one mentions, does have a fault return probe that is not shown but it does mention that it does locate faults.

    I bought it from a POCO that wasn't using it anymore.

  10. #10
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    Thanks for all your opinions. I appreciate it.

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