Looking to up grade my electrical service to 200 amps. I'm going to hire and electrician to do the main hookup to the outside disconnect and the new 200 amp panel. I'm looking to do the inside wiring myself. The new panel is going to be in a different spot than the old one (about 20 feet away). Can I (temporarily) treat the old panel as a subpanel while I bring over the main lighting circuits one by one?