Posted by sailplane on Aug 11, 2017; 2:57pm
URL: https://www.es-forum.com/Grounding-Shielding-tp4030801p4030807.html

Fog Top wrote

My guess is that you've connected to earth carrying a magnetic field from the area-wide electric system.  

I measured magnetic.. It doesn't increase when I ground it.

But I did just find unusual magnetic fields in my basement where the panel ground hooks up to the water pipe.
The grounding wire has 10mG on it, .. is this normal?
It seems to give off some magnetism into the water line, but once it goes through the water meter it reduces a lot.
I also tried turning off the Main power, and surprisingly the magnetic field got even higher!.. Like double or tripe.

Why would turning off the power to the entire house raise the magnetic field?  Also, I keep a lot of breakers off when I don't need them, and turning more on seemed to reduce the magnetic field, but only by 0.1mG.

I don't have any experience with magnetic fields,.. What causes them in the first place?.. There is no E field on that ground wire.