Originally Posted by
Sly
http:///forum/post/2714069
This test is inconclusive. When you ran an independent ground to a copper water pipe you created a ground loop. In other words, the ground your house is using is not the same ground that the GFCI is using. Often times you will have a voltage difference when you run two independent grounds like this.
Your house DOES have a ground... just not one run separately like modern day wiring. The neutral on your outlet is run to ground. This is either the wide blade (on a polarized outlet) or the white wire (if they even wired it correctly). I'll bet that if you check the voltage between your neutral wire and the ground wire that you created, you will see that they are not showing 0 volts. There will probably be SOME voltage between the two even though they are both technically a ground.
Do you ever have a problem with your GFCI tripping?
I personally wouldn't worry about 0.8 volts in my tank. It is probably an error on your testing method due to there being a ground loop. I had stray voltage once and it was more like 20 volts. It turns out my UV light had water leaking through it due to a bad seal and was energizing the water.
FYI, if you do have a voltage leak, it will be AC not DC. If you are showing DC voltage then that is not a voltage leak. The saltwater acts as a conductor and when you stick two dissimilar metals in the tank they can create DC voltage just like a regular battery.
why would the copper pipe create a ground loop it is also bonded to your ground system and the cold water line is the main ground in a home service if you have metal pipes and city water