Personally I've always seperated Lighting and Socket-Outlet loads as far as an RCD goes. AS/NZS 3000 requires that you have at least 2 RCD protected Lighting circuits and at least 2 RCD protected Socket-Outlet circuits. Considering that most home-owners don't even know that thier house even has RCD's in it, it seems rather rich that most of the call-outs here are to do with RCD's. In the worst case scenario, we have had them by-passed here.