Richard Karasik

Ok this makes sense and it may also account for the slight differential i am seeing- this old house has part galvanized and part copper - so the "grounding potentials" are different between the two metals. Epecially since the two types of metals are only bonded by a mechanical connection ( union or other joint) Hmm Time for a revamp - THanks for all the help

That figures we get lightning once every 15 years here off in the mountains .

Kind of funny considering an electrician put it in and the city inspected it .. What is the purpose of grounding to a copper pipe and a separate copper ground driven into the ground if i may ask ...

Hmm COuld explain a lot of problems with this old house. 1 3 foot copper ground rod near main box, 2. Also tied into the copper plumbing under the house. I think i have to get this re-engineered.

IN terms of modern wiring -- is not the ground wired up to copper rod jammed into the ground. Why not add an additional copper rod for a ground in the location of the house that needs 3 wire? I have one old room with 2 wire 90 feet from any box. The choice is $1000 worth of wiring of 3 wire, 2 wire GFCI or maybe driving another ground and doing 3 wire- why is that last one not a good solution?