230.70(A)(1)
(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.
Note that it does not say how far you are allowed to enter a building or structure. This leaves that decision up to the installer and the AHJ. Most AHJ have made rules on what is acceptable for the distance allowed. Many are in the 3 to 5 feet of conductor range, from what I understand from some that have posted on this site, some places will not let you enter a building at all and your service disconnect must be outside.
Where I live they have chosen 5 feet as the maximum amount of service conductor allowed to enter a building or structure. A crawl space is inside the structure. You can run the conductors on the outside as far as you wish, you could wrap the building multiple times if you wish and not be in violation of this particular section.
You can however if you wish run service conductors in the ground under the building and then penetrate the floor on the lowest level. Wherever you penetrate the floor you are now inside and whatever limits your AHJ has set start there. If under the building is crawl space with no concrete floor or less than 2 inches of concrete then it must be buried under at least 18 inches of dirt.
You can also encase your service raceway in 2 or more inches of concrete or run them in any vault that meets the construction requirements of Article 450, Part III and they are still considered outside the building according to 230.6.
I have used these rules many times to get the service to an interior room without having to have the service on the exterior of the building, or in a place that is otherwise not desired to have it by the owner/occupant. In fact my own house is this way, mechanical room is in about center of house in basement, service conductors are in the ground under the basement floor and emerge in the mechanical room and main panel with service disconnect is installed in mechanical room. Most of the larger branch circuits are feeding loads near this area so there is less length to these circuits requiring larger conductors than there would be if I had placed the service near an exterior wall, plus I would have had a disconnect or panel either outside or in a habitable room.