I just dug an 18" deep trench from the house to my detached garage and I'm about to run 3-gauge service cable for my new 100-amp sub panel. The garage is only 10 feet away from the house. The cable will be encased in PVC conduit. The main 200-amp service panel at the house is well-grounded, and a couple of electricians here in LA have told me that I don't need any additional grounding rods for the sub-panel, just a green grounding wire that will get run back to the main service panel.

Anybody know what size wire I need for the green ground wire? I think I read 8 someplace, but I want to be sure.

Thanks!

- Jason