What is the minimum service size(in amperes) that can be installed for a non residential building? I have a stand alone garage that is being left on a piece of property and the house is being demolished. The garage originally fed from the house at 120/240V 1 phase 40 amp. Is this governed by the poco or by the code? I know the min for a dwelling is 100A, but don't know about an indv building. Thanks.