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Thread: Equipotential bonding grid at pool

  1. #1

    Equipotential bonding grid at pool

    Need assistance with stray voltage at pool. Here's the situation. The only thing bonded at the pool was the metal pool light and the pool cover motor. The grounding of the pool light introduced the pool water to the neutral at the neutral to ground bond in the main panel. The customer complains about the 0.7 volt tingle shock. Most of the 0.7 volts is the voltage drop on the primary system as imbalance current travels back to the substation (Ohm's Law).

    The problem is that the pool builder used some kind of fiberglass strands mixed in the concrete and no rebar or any equipotential plain. This appears to be a violation of NEC 680.26, since no equipotential bonding grid was installed. I had them bond the hand rail and pool cover to the cover motor chassis which eliminated the potential difference from the cover track and the water. The customer still feels a tingle at the end of the pool. Just from the concrete to pool water.

    Does anybody know if this type of concrete reinforcement is allowed? What is the usual methods for adding a equipotential bonding grid if fiber concrete or epoxy coated rebar is used?

  2. #2
    Join Date
    Dec 2003
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    TAMPA FLORIDA
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    Re: Equipotential bonding grid at pool

    I do know there is fiber concrete but think it would be crazy to use on a pool.Its asking for a crack that can never be fixed.As far as nec i am not sure it violated any codes.
    Lets not forget there have been fiberglass pools for many years

    [ July 22, 2005, 05:42 PM: Message edited by: jimwalker ]
    Tampa Florida

  3. #3

    Re: Equipotential bonding grid at pool

    Fiber reinforced concrete stops the small cracks better than reinforcing mesh. It is a good choice for the deck area, except for hard to get a pretty finish due to the fiber. Nothing wrong with putting it in the pool walls, but there had better be some steel in there too

    Probably there is steel in the walls, just not bonded to anything.


    Jim

  4. #4
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    Re: Equipotential bonding grid at pool

    Fiber on pool deck will cut feet.Any steel if used must be bonded.
    Tampa Florida

  5. #5
    Join Date
    Aug 2004
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    Re: Equipotential bonding grid at pool

    it is no more difficult to repair concrete cracks in concrete reinforced with fibers than with steel. the difference is that the fiber reinforced concrete is far less likely to crack in the first place.

    my guess is that even if they used fiber reinforced concrete they also had some steel in the concrete as well.

    <added>
    use of fiber reinforced concrete does not eliminate the need for a bonding grid (or at least so says my limited understanding of this whole subject). possibly the builder thought that building it w/o steel eliminated the need for the bonding grid, much as doing this in a foundation would eliminate the need for a Ufer connection.

    [ July 25, 2005, 09:25 AM: Message edited by: petersonra ]
    Bob

  6. #6

    Re: Equipotential bonding grid at pool

    Thanks for the discussion. I've completed my research and NEC article 680.26(C) clearly states that the alternate reinforcing is allowed. However, that does not exempt the pool builder from installing a equipotential bonding grid from the the decking (3'horizontal from the pool). Needless to say the pool builder is not happy with my research. I'm going to meet with the local electrical inspectors to discuss this new problem.

  7. #7
    Join Date
    Jun 2005
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    15

    Re: Equipotential bonding grid at pool

    I have worked on pool decks with fiber concrete and AHJ in my county strictly enforces equipptential bonding with ground ring and lateral spacing 680.26(C). Grounding and bonding very important here in North Florida and rightly so.

  8. #8
    Join Date
    Dec 2003
    Posts
    27

    Re: Equipotential bonding grid at pool

    Know this is not likely your situation - do you realize that pools located near utility transmission lines can become a charged capacitor unless pool water and pool grounding system are connected with a metal ground ring in the water around the pool? This is one of the reasons that utilities get 100 foot right of ways. Of course some stupid people put pools where they should not.

  9. #9
    Join Date
    Feb 2003
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    Florida
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    7,286

    Re: Equipotential bonding grid at pool

    Can you please describe how this happens? I have never heard this before and would like to understand how this is possible. Thanks.
    Bryan P. Holland, MCP

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