Q. When does the NEC consider service conductors as being installed outside of a building?
See the answer below.
This answer is based on the 2017 NEC.
A. Conductors are considered outside of a building when they’re installed [230.6]:
(1) Under not less than 2 in. of concrete beneath a building.  
(2)Â Within a building within a raceway encased in not less than 2 in. of concrete or brick.
(3)Â In a vault that meets the construction requirements of Art. 450, Part III.
(4)Â In a raceway not less than 18 in. below a building.
(5) Within rigid or intermediate metal conduit that passes directly through an eave but not a wall of a building.
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About the Author
Mike Holt
Mike Holt is the owner of Mike Holt Enterprises (www.MikeHolt.com), one of the largest electrical publishers in the United States. He earned a master's degree in the Business Administration Program (MBA) from the University of Miami. He earned his reputation as a National Electrical Code (NEC) expert by working his way up through the electrical trade. Formally a construction editor for two different trade publications, Mike started his career as an apprentice electrician and eventually became a master electrician, an electrical inspector, a contractor, and an educator. Mike has taught more than 1,000 classes on 30 different electrical-related subjects — ranging from alarm installations to exam preparation and voltage drop calculations. He continues to produce seminars, videos, books, and online training for the trade as well as contribute monthly Code content to EC&M magazine.