Could someone who has a grounding box take a voltage measurement between one of the ground terminals on their grounding box and the “D” shaped hole in their wall outlet? I’m curious if a voltage differential exists. I imagine it will be in the microVolt range if at all. The D shaped hole in the wall plug should go to the earth ground outside of your home so virtually no risk plus a voltmeter has a high resistance across the leads. Put the red lead in the D hole and the black lead on the grounding box terminal. I would expect a positive voltage reading if anything.
Grounding cable gauge size
For those of you using external grounding source devices, units such as Entreq, Nordost, Synergistic, etc. What size wire gauge seems to work the best?
ozzy