Article 225 of the 2014 NEC provides requirements for running branch circuits outdoors, on or between structures (including buildings and poles). Pay special attention to Table 225.3. It lists specific cases of equipment and conductors, showing which other Articles apply. If you’re installing outdoor receptacles at a marina, you need to also apply Art. 555.
But what if you find conflicting requirements between Art. 225 and the one from Table 225.3 that applies to your particular special case?
The way the NEC is arranged solves this dilemma. Chapters 1 through 4 apply to all installations except as amended by the relevant Article(s) from the remaining Chapters. So in the case of a conflict, you apply the requirements from the Article identified in Table 225.3.
While you still determine ampacity per Art. 310, ampacity isn’t the only factor in determining the minimum size of conductors run outdoors. If they run overhead, they can’t be smaller than 10 AWG copper or 8 AWG aluminum for spans up to 50 ft (up to 1,000V, without a messenger wire) [225.6]. Longer spans require 8 AWG copper or 6 AWG aluminum.
