National Electrical Code Articles and Information

National Electrical Code Top Ten Tips: Article 555, Marinas and Boatyards

1. Article 555 covers the installation of wiring and equipment for just about any place where boats are docked, repaired, or fueled. This used to exclude private and non-commercial docking facilities of single-family dwellings in older editions of the NEC, but they are also covered [555.1].
    
2. The Electrical Datum Plane is the most important concept of Article 555. The definition, once in 555.2, is now in Article 100. Understand that this plane is defined based on the highest water level (e.g., tide), not some average. The electrical datum plane distances are laid out in 555.3.
    
3. Pier power distribution systems cannot exceed 250V phase to phase (nominal) [555.5].
    
4. Transformers and their enclosures must be identified for wet locations [555.7(A)].
    
5. Permanent safety signs must give notice of electrical shock hazard risks, and must comply with the three requirements of 555.10(1), (2), and (3).
    
6. Bond everything metallic that is non-current carrying [555.13] but that could become energized.
    
7. Many older sections have been removed over time. For example, 555.15, 555.17. 555.19. and 555.21 all appeared in the 2011 NEC. The 2020 NEC omited these, going from 555.13 to 555.30. But with the 2023 revision, we have 555.14 (equipotential planes and bonding) and 555.14 (replacement of equipment).
    
8. Locate electrical enclosures such that they do not interfere with mooring lines [555.31(B)].
    
9. When you bond per 55.13 and 555.37, ensure your equipment grounding (bonding) conductor is an insulated conductor sized per 250.122 but not smaller than 12 AWG [555.37(B)].
    
10. Each floating building must be served by one set of feeder conductors from its service equipment [555.51].