It used to be fag packet type approximation that when measuring the earth impedance that as a very very much rule of thumb starter for ten sort of thing.
approx 80% of the total figure between two fart away points might be made up of the area around the local rod/plate/tapes etc and the other 20% between that area and all the area between them up to the area surrounding the other earthing point.
What would be a sort of max in ohms between two extremely far points example two countries ? say England and New Zealand or Oz?
