i have a new customer who is building a 4700 sq. ft. home with a pool and spa. he also plans to build a pool/guest house of about 1000 sq.ft. he insists on only having a 200A service. i told him that thr load calcs say he needs a 400A service. now he thinks im trying to get over. Am i correct and he's just a moron?

For a true evaluation you will have to show us how you arived at your calculations.

Roger

Here is a link you can try. It is Canadian, but hey...demand is demand for a quick reference. http://www.codemath.com/cgi-bin/Run.pl?script=Cec8_200

That's a neat calculator. Just for fun I punched in the numbers for a known house and it came back with a demand of 21kW. (Not really relevant as I'm in Europe, but hey demand is demand ) What kind of service would you use for this in US/Canada?

the service is for the us

We'd use a minimum 100 amp service for a 21 Kw (88 amp)house demand load. (Canada)