Re: sizing service
In my opinion, no. When there is more than one panel the service calculation and panel feeder calculations use different diversity factors. I use the method in 2005 NEC 220.82 for single family residential service calculations. For a feeder to a sub-panel I can only take diversity for what's actually on the panel, using the factors in 220.42 through 220.62, as applicable. I frequently find homes where the calculated service load is well below 400A but there's no way to distribute the loads on two 200A panels because of the differences in the demand factors. I know some designers who put the cooktop on one panel and the oven on the other and use the 220.82 method for each panel on the basis that each panel includes fixed cooking, but my opinion is that's an end run around the intent of the Code.
Martin
