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National Electrical Code Articles and Information

NEC Quiz: Article 314, Part 7 Answers

by Mark Lamendola

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  1. It must completely enclose the device on sides and back, provide substantial support for the box, and not have its mounting screws serve double duty as device supports [314.19].

  2. A quarter inch [319.20].

  3. An eighth inch [319.21].

  4. Zero. Use the correct depth box. If you need a surface extension, you can use an extension ring listed for the purpose [312.22]. You can't use another box as an extension ring.

  5. It can contain splices and splicing device, but no other devices. It can support equipment such as a luminaire or ceiling fan. It can't be bigger than a hundred square inches (the NEC doesn't specify a max depth or volume). It must have threaded entries or hubs identified for that purpose. It must be supported by at least two raceways, each of which must be supported within 3 feet of the box (or 18 inches of the raceways are on the same side of the box). You will find these requirements, and five exceptions, in 314.23(E).



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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