Have an existing underground 15a service (14-2) from home panel to garage. wishing to add more plugs and lights in the garage. Planning to put in a sub panel (four breaker) and add plugs and flourescent lights. I will use gfi's at the start of plug strings. Needing recommendations as to breaking up of circuits for best results. (ie: lights all on one, and plugs separate, or??) By the way this garage is not attached. Do I need a ground rod etc from sub panel?? Any input would be greatly appreciated.