grounding question

Discussion in 'General Electronics Chat' started by sonoman, Dec 1, 2012.

  1. sonoman

    Thread Starter New Member

    Dec 1, 2012
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    Two steel tanks off my well developed pin-hole leaks in the past 10 years, the first tank (which was installed in 1996 when the house was built) and a galvanized tank I replaced it with about 5 years ago. After the galvanized tank failed, the guy at the plumbing supply shop suggested it may be caused by electrolysis, due to an improper ground. The system is plumbed with PVC, but he said there may be a voltage (current?) running through the water, causing my steel tanks to fail.

    When I checked the ground lug on my well control circuit (240v), I see about 0.4V between the ground lug and an earth ground. Is that something I should be worried about and should I ground the well with a ground stake? I expect the well is grounded since it is in the ground already. What would cause this difference?

    I replaced the galvanized tank with fiberglass, but if there is a problem, I don't want to push it downstream to attack my copper pipes.


    thanks
     
  2. kubeek

    AAC Fanatic!

    Sep 20, 2005
    4,670
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    Normally you should use a zinc sacrificial anode connected to the steel tank which then corrodes instead of the steel. Do you have anything like that installed?
    Can you disconnect the ground lead going to the tank and measure the current?
     
  3. sonoman

    Thread Starter New Member

    Dec 1, 2012
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    0
    There was no sacrificial zinc anode in the galvanized tank. The anode in my water heater is barely touched after 15 years.

    I had to replace the galvanized tank because it was leaking (spraying) water all over my well shed. I have a fiberglass tank in there now, which won't corrode but may mask a problem.

    I don't have a ground wire on the tank. It is a retention tank to mix chlorine solution that gets injected into the water system. The tank is plumbed with PVC so it has no direct electrical connection, just what goes through the water itself.

    As I noted, I have about 0.4v at the ground lug relative to an independent earth ground. I can check for a current from the ground lug to the independent ground.
     
  4. kubeek

    AAC Fanatic!

    Sep 20, 2005
    4,670
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    Not inside, i meant an anode outside the tank. Or actually, is the tank corroded from inside or outside?
     
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