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I am trying to have "cable" installed. The installer clamped on to the "ground" cable on the outside of my building and read 0.5 to 3.3 amps, so he would not install cable until the reading is less than 0.3 amps. I've had electricians and the utility company out to try to resolve the problem. They all can't figure out what the problem is.

There are two "ground" cables coming out of the meter box, one goes to the ground rods, the other to the water pipes. When measured individually there is 0.0 amps on the ground rod line, and 0.3 to 3.3 amps on the water pipe ground side. These two lines are bonded together in the meter panel and are tied together until the ground connected to the water line goes into the house. When the ground on the water pipe is disconnected from the water pipe, both grounds measured from the meter panel read zero. Any ideas?

The Electricians disconnected the cable to the water pipes, the cable read zero. We checked the individual sections of the water pipe, without the cable connected they read zero, with the cable connected each leg read about 0.2 amps. While disconnecting the cable from the water pipes there was no evident spark. All the breakers on the meter panel were disconnected, and the meters were removed one at a time, no significant difference. Turning off the individual breakers in the inside panel makes no significant change. With the water pipe cable disconnected, the ground-rod cable still reads zero. The ground-rod cable connections were checked and both seem bonded well in the ground. What's really strange is that both the water-pipe cable and the ground-rod cable are bonded together in the meter panel. Clamping on both cables 12" below the meter panel they read 0.3 - 2.0 amps. Reading the water-pipe cable at the same point alone reads the 0.3 - 2.0 amps while the ground-rod cable still reads zero. We saw a fluctuation up to 3.3 amps when my refrigerator started, but then goes back to the 0.3 - 2.0 amps on the water-pipe cable. This is an old (1740) house that was refurbished in the early 80's. New wiring throughout. The meter panel was replaced about 8 - 10 years ago. I've had three electricians here along with the utility company electrician. So far no-one has an answer.

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  • are you certain that they were measuring current?
    – jsotola
    Dec 28, 2019 at 14:11
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    It sounds like something is electrifying your water pipes, either inside or outside the house. To determine which, try reconnecting the wire to the water pipes, and then measure the current on the pipe itself, on both sides of that connection -- between that connection and the rest of the house, and between that connection and the street.
    – Dave Tweed
    Dec 28, 2019 at 14:25
  • When it is disconnected from your water pipe, does it throw a spark? Dec 28, 2019 at 15:26
  • Did you try throwing breakers off (starting with water heater) to see if the source of current is coming from in the house? Dec 28, 2019 at 15:49
  • Where are you on this planet? Does turning a specific breaker off in the panel cause the current on the water-pipe bond wire to go away? Dec 28, 2019 at 21:15

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Your water heater, washing machine etc. has a ground fault

It is actually shorting out, and the electricity is going down the water pipe instead of (and possibly in addition to) down the proper ground wire to that appliance.

I would carefully inspect the ground wires for those appliances (*watch it, they may be hot, especially if disconected!). I would also put a clamp meter around their entire cable (normally you'd never do that, but it will work for detecting ground faultss being returned externally).

You can also try shutting off every breaker in the house until it goes away. I like to shut off half the breakers, narrow it down to which half of the panel it is, then split that half in half, and see which half-half it is, the. Subdivide that half, etc. After 5 rounds you will have narrowed it down to one breaker.

Keep in mind the problem may only appear at times, e.g. When the water heater is cycled on.

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    Also, with metal water pipes, putting the clamp meter around the water pipe should read current if there's current flowing down the water pipe... Dec 29, 2019 at 20:06

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