When calculating what size of service is necessary for a remodel......Am I to add all breakers? And the total number is the size needed? Seems a little excessive. For instance; There are two AC units which require both a 60 amp and a 30 amp for each. That alone is 180 amps. By the time you add the kitchen, water heater and all the receptical and lighting circuits, we're up to 400 amps. So is that what I need?