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National Electrical Code Articles and Information

Based on the 2011 NEC

by Mark Lamendola

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, except private and non-commercial docking facilities of single-family dwellings [555.1].
  2. The Electrical Datum Plane is the most important concept of Article 555. Read 555.2 very carefully. Understand that this plane depends on the highest water level (e.g., tide), not some average.
  3. New with the 2011 NEC is a requirement for the main overcurrent protective device to be GFCI-protected (with a max of 100mA) [555.3].
  4. The bottom of enclosures cannot be below the level of the electrical datum plane [555.5].
  5. You cannot place the service equipment on the floating structure [555.7]. The rationale for this is similar to the rationale for not permitting service equipment to be mounted on a mobile home. The key concept here is movement.
  6. It's important to keep overhead conductors away from moving boats. Thus, you must route overhead conductors and cables in a manner that avoids having them closer than 20ft from the outer edge or any portion of the yard that can be used for moving vessels, stepping masts, or unstepping masts [555.13(B)(1)].
  7. The title "Grounding" for 555.15 does not match the text in 555.15. See the definitions of grounding and bonding in Article 100. What 555.15 means is bonding, not grounding.
  8. You must provide a disconnecting means to isolate each boat from its supply connection(s) [555.17].
  9. Receptacles supplying shore power to boats must be housed in marine power outlets or listed for the conditions of use [555.19(A)].
  10. Fuel dispensing stations must comply with Article 514 requirements, in addition to complying with Article 555 requirements [555.21].

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How the NEC is arranged

  1. The first four Chapters of the NEC apply to all installations.
  2. Article 90 precedes Chapter One, and establishes the authority of the NEC.
  3. Article 80 follows the body of the NEC; it exists as Annex H. It provides the requirements for administration.
  4. Chapters 5, 6, and 7 are the "special" chapters, covering special: occupancies, equipment, and conditions (in that order).
  5. Chapter 8 provides the requirements for communications systems.
  6. Chapter 9 provides tables.
  7. The appendices provide mostly reference information.
  8. Appendix D contains examples that every NEC user should study.

Try your NEC moxy:

  • Do you know the difference between bonding and grounding? Hint: Look in the NEC, Article 100.
  • Does the NEC refer to grounding incorrectly in any of its articles? Yes! So be careful to apply the Article 100 definitions. Don't ground where you should bond.
  • When doing motor load calculations, which Article covers hermetic motors? Answer: While Article 440 covers the application of hermetic motors, it does so only by amending Article 430 because hermetic motors are a special case of motors. For motor load calculations, refer to Article 430.
  • Does the NEC provide a voltage drop requirement? Yes! It does so in a special case, which is Article 648 Sensitive Electronic Equipment. But for general applications, it does not provide a requirement; it merely provides a recommendation in a couple of FPNs.
  • Take our Code Quizzes.

Remember other applicable codes, rules, standards, and references:

  • OSHA's electrical worker safety rules.
  • IEEE standards.
  • NETA standards.
  • NFPA standards.
  • International Codes (if applicable to the installation).
  • State Codes (if the state has them).
  • Local ordinances and permit requirements.
  • Local fire codes.
  • Manufacturer requirements or guidelines.
  • Customer security requirements.
  • Industry standards.
  • Your company's own internal standards, practices, and procedures.
  • Engineering drawing notes.




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