Water pipe ground?

Question

I am rehabbing a property and it did not have a ground rod. I drove one in and connected it to the electrical box with solid copper wire as it should be. I am removing all of the old galvanized plumbing and replacing it with cpvc. When I disconnected the grounding system from the old galvanized pipe, 1/2 of the elctircal box gained 9 volts and the other half lost 9 volts. When re-connected, both legs of the box read 118.6.

The ground rod, nor the ground from the pole do not seem to matter as much as the water pipe ground. Why is that?

Any advice would be appreciated.

Answer 1

When you disconnected your old ground you lost your neutral(white wire) bond to ground. The neutral wire must be connected to your ground wire at your service/panel or your 2 lines or hot legs will fluctuate depending on the difference in current between the legs. I've seen one leg shoot clear up to 200 volts while the other dropped down to next to nothing. It's not good. You might want to unplug your computer til you get it fixed.

Answer 2

You could have bonding problems at the box, the ground rod, or both. Additionally, the ground may be improperly sized (the rod or the cable).

This is the time to call in a professional... you could be creating a hazard for every future tenant, guest and tradesman.

If I saw the change, I would definitely throw a red flag.

Answer 3

you need to drive another ground rod 6 ft from the other and connect it to the other ground rod with solid copper wire and make sure the the neutral in your box is bonded to your box...the water line gave more grounding area for the ground system