Main disconnect box before service panel
I am installing a new service panel in a small building. I have the masthead, meter box and temporary service available outside the wall. I'm going to go straight through a brick & cinder block wall and put in a service panel. I'll have a licensed electrician do the high voltage hookup. Question is.. I'd like to put a separate main disconnect, like a lockable double throw switch, before my service panel, which, of course, will have it's own main disconnect. I want to do this so I can totally disconnect power and work on the service box without having any hot wires near me. It would also be nice if the disconnect box had a single outlet that I could use for temp power prior to the disconnect. Is anything like this possible ? Thanks..