Chapter 2 of the NEC has a logical progression of five Articles that run from 210 through 230. The first three provide the requirements for branch circuits, feeder circuits, and their calculations. Article 230 provides the requirements for services.
The first three Articles assume the circuits are inside a building. If they aren't inside a building but run on it or attach to it, they must also meet the requirements of Art. 225 [225.1 and Table 225.3].
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