Technically the service disconnect just has to be on the property but your AHJ may still want a disconnect on/in the building. Yes that will become a feeder and you need to run the ECG along with a ground. As long as that is the feeder for the whole building, you can use 210.15(B)(6) in a dwelling. (Not commercial)
Last edited by gfretwell; 04/15/1103:04 AM. Reason: Make the correction Niko pointed out
Be cautious on the location 'within the building'. Unprotected, unfused, conductors within a building, the distance allowed is not specific in the NEC. For the most part, it's left up to the local AHJ. I hear 12", 5', 3'4", but there is NO distance within the book & never was.
A main inside is accepted 'nearest to the point of entry', unless we use the 2" of concrete/brick exception. It all boils down to the AHJ's 'nearest' definition