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Thread: Shock at faucet.

  1. #1

    Unhappy Shock at faucet.

    Home owner say's that they are getting shocked from the bath tub's faucet. I have checked everything that I could think of. I installed an 8ft ground rod, properly bonded electrical system to the water meter and made sure that the point of attachment is tight. I also made sure that the connections in the new meter can and the new "Cutler Hammer" panel are tight. I installed the panel and the grounding system 6 years ago.

    The water pipes are completely exposed in the basement. I grounded the hot/cold water supply pipes at the location where they accend to the bathtub.

    This is a natural gas hot water tank and the water is supplied by the municipality ( City of Detroit). The pipes are galvanized. No plastic can be seen. I don't know what's behind the walls.

    This problem is inconsistant. It initially happened in Oct 2006. The home owner called me today and told me that the problem is re-occuring.
    If it don\'t make dollars...it don\'t make sense!

  2. #2
    Join Date
    Jan 2007
    Location
    Columbus, Oh
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    460
    1. Does the residence have a water softener?
    2. I guess you could always go out there and verify with a meter.
    3. You think maybe you set up a ground loop?
    Just trying to help...
    I found my easter eggs & my car keys, life is good!

  3. #3
    Join Date
    Apr 2006
    Location
    Portland, OR
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    2,341
    What sort of tub is it (eg cast iron or other metal, or is it fiberglass/plastic), and what sort of drain line is there (eg cast iron, copper, pvc, etc.) ?

    One possibility is that there is a metal drain line that is an inadvertent grounding electrode not bonded to the building grounding electrode system. If there is a bad neutral anywhere (including at the POCO pole) then all of the bonded metal in the house will be raised to the neutral potential, but a separate grounding electrode will show a voltage difference, since it is at 'ground' potential but the neutral is at 'elevated' potential.

    Also, if you have separate earth electrodes, if there is any earth current (caused by electrical systems entirely outside of the house) than this can present as a voltage between separate earth electrodes. (I am saying 'earth electrodes' rather than 'grounding electrodes', to include metal that is in incidental electrical contact with the earth and which may not count as a grounding electrode, for example a cast iron pipe that is partially embedded in a concrete floor.)

    I don't believe that there is any _requirement_ to bond drain lines to water lines or the GEC, since this would be 'other metallic piping', and not likely to be energized, and it is quite possible that any underground section would be too short to count as a grounding electrode. But I do recall periodic reports of people getting shocked between grounded and bonded pipes and their drains, or grounded and bonded pipes and soil.

    See for other reports:
    http://www.electrical-contractor.net...ML/003683.html

    http://www.electrical-contractor.net...ML/003127.html

    -Jon

  4. #4
    Join Date
    Jun 2003
    Posts
    756

    Shock at faucet

    Quote Originally Posted by torint
    Home owner say's that they are getting shocked from the bath tub's faucet. I have checked everything that I could think of. I installed an 8ft ground rod, properly bonded electrical system to the water meter and made sure that the point of attachment is tight. I also made sure that the connections in the new meter can and the new "Cutler Hammer" panel are tight. I installed the panel and the grounding system 6 years ago.

    The water pipes are completely exposed in the basement. I grounded the hot/cold water supply pipes at the location where they accend to the bathtub.

    This is a natural gas hot water tank and the water is supplied by the municipality ( City of Detroit). The pipes are galvanized. No plastic can be seen. I don't know what's behind the walls.

    This problem is inconsistant. It initially happened in Oct 2006. The home owner called me today and told me that the problem is re-occuring.
    I would start by looking for an open neutral. Using an amprobe check to see if there is current on the gec or ground rod if there is 1,if there is current flow on the grounding electrode system it could be an indication of an open neutral. Remember that the open neutral could be at a neighbors home.

    There is a good article titled The Shocking Truth About Grounding Electrode Conductors at EC&M http://www.printthis.com/pt/cpt?acti...ctrode+Conduit... I am not sure if that will work but I gave it my best.

    I would call the your power company and ask them to check connections from their transformer to the home service entrance.

  5. #5
    Join Date
    Dec 2004
    Location
    Fort Collins, CO NEC: 2014
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    Quote Originally Posted by torint
    Home owner say's that they are getting shocked from the bath tub's faucet. I have checked everything that I could think of.
    Did you take measurements from the tub faucet to other points within reach?
    Did you shut off the service and determine whether the voltage remained or not?

    I installed an 8ft ground rod, properly bonded electrical system to the water meter and made sure that the point of attachment is tight.
    Six years ago, or in October 2006, or recently? If the water system was not connected to the electrical system, and then you connected it, and then the service neutral on the utility side opened, then the faucet could start shocking the user because of the connections. The unbalanced neutral current, unable to return to the source by the service neutral, would begin using all paths to return to the grounded utility source.

    The water pipes are completely exposed in the basement. I grounded the hot/cold water supply pipes at the location where they accend to the bathtub.
    What exactly did you do to 'ground' this point?

  6. #6
    I thought about the "ground loop" but the problem was happening before I grounded the hot/cold supply where it accends to the tub. Once I grounded the hot/cold supply, the problem seemed to be fixed. Now it is back. So what I'm saying is: if I possibly set up a ground loop then why did the problem stop.
    If it don\'t make dollars...it don\'t make sense!

  7. #7
    George, I installed the system and correctly grounded it 6 years ago. I upgraded it from a 60a system to a 100a system. It was properly gronded and bonded to the water system at that time.
    Turning off the main and checking for power is an action that I will take... thanks.
    As far as the hot/cold supply grond is concerned, I installed a water clamp on each pipe and ran a piece of #6 copper back to the supply side of the water meter.
    If it don\'t make dollars...it don\'t make sense!

  8. #8
    Join Date
    Dec 2004
    Location
    Fort Collins, CO NEC: 2014
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    Quote Originally Posted by romeo
    There is a good article titled The Shocking Truth About Grounding Electrode Conductors at EC&M....
    I couldn't get your link to work, try clicking here to see the article. I agree, it's an excellent one. :cool:

  9. #9
    Join Date
    Apr 2006
    Location
    Portland, OR
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    David's ground loop question brings up an interesting theoretical possibility, one suggested by the EPRI article on EMFs and cancer links.

    If you can follow a continuous conductive loop, eg. water faucet to water pipes to electrical system bond to grounding electrodes to drain pipes to shower drain, then any changing magnetic field coupled with that loop would induce a voltage in the loop. Such magnetic fields could be created by power lines (the point of the EPRI study), but more likely would be created by improper wiring in the home. In particular, any circuit that violates 300.3(B), or where the current flow of a conductor is not balanced by return current in an adjacent conductor.

    I would be _very_ surprised if the voltage induced in such a 'ground loop' was enough to produce a perceptible shock, but this dose present an interesting possibility to explore if others turn out to be blind alleys.

    -Jon

  10. #10
    Join Date
    Dec 2004
    Location
    Fort Collins, CO NEC: 2014
    Posts
    15,472

    Talking

    Jon, you are a genius among us open-mouth-breathing dullards.

    Let's eliminate the easy option first.

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