Im at the planning point of upgrading my house electrical system. Currently I have 150 amp service and a 150 amp panel. My panel is old and has no main on/off switch. I will eventually need to upgrade my service and plan on going to 200 amp. My question is, can I swap my panel for a 200 amp panel now, and just swap the main on/off breaker with a 150 amp one until I change the service. Then put the 200 amp breaker back in.