I'm looking for the NEC code reference that allows a main panel within a home to contain a main breaker because the meter is directly on the other side of the outside wall, versus installing a meter-main outside. I remember hearing something to the effect of no more than 5 feet of service cable between the two boxes.
Article 230 Services
VI. Service Equipment — Disconnecting Means 230.70 General
Means shall be provided to disconnect all conductors in a building or other structure from the service-entrance conductors.
The service disconnecting means shall be installed in accordance with 230.70(A)(1), (A)(2), and (A)(3).
(1) Readily Accessible Location.
The service disconnecting means shall be installed at a readily accessible location either outside of a building or structure or inside nearest the point of entrance of the service conductors.
In Canada, the provincial Inspection Authorities issue Bulletins that put specific allowable lengths on the distance service conductors in conduit may run inside a building. So the precise distance varies with the jurisdiction, anywhere from 1.5m (59") to 6m (20'). The reason you can't find any mention in the NEC is probably similar.