I'm replacing my old meter housing with a combo unit (meter/breakers) Since I just bought the house and the meter had been pulled, I wanted to make sure I was up to code when the electric company comes back out to put power on the house. I currently have only one grounding rod and I am told I need two. (I believe this is for NEW construction, but will check this out with electric company.) Anyway these two rods are supposed to be six feet apart. How deep does the copper wire connecting these rods have to be?