When adding a subpanel in a detached building, I know we have to run 4 wires. Do we have to drive 2 grd. rods at the separate building like we do at the main service? And when we do drive our ground rods, and run our ground wire to the grounding bar,it will be tying the two ground systems togethers. Is there something about the grounding impedance difference here? I probably didn't word that right, but I'm sure someone will pick it up:) Steve...
