The grounding wire can be any heavy-gauge solid copper wire, you can get that anywhere. And thanks for mentioning the drip-loop, Bitt, I forgot about that. (Dan, the drip-loop simply puts a little "U" shape in the cable so that rainwater drips off the bottom of the U instead of collecting at the grounding block or into the hole you drilled in the side of the house. To know the proper place to put a drip loop, imagine that you're a drop of water, where would you go.)