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National Electrical Code Articles and Information

NEC Quiz: Article 408, Part 3 Answers

by Mark Lamendola

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  1. You must close them using identified closures (that certainly eliminates cardboard for this purpose) or other approved means (that certainly eliminates duct tape for this purpose) that provide protection substantially similar to the wall of the enclosure (that certainly eliminates layers of phasing tape for this purpose) [408.7].

  2. Yes, you can. But the installation must conform to 312.2 [408.16].

  3. From a Code standpoint, yes you can. But of course you should not unless there is a compelling reason to do so. And if you do so, then place them in a way that reduces to a minium the probability of communicating fire to adjacent combustible materials [408.17]. Take additional measures as feasible, for example providing a barrier or a room with positive pressure but vented to the outside away from the materials.

  4. Three feet is only the bare minimum under some conditions; under others, a greater distance is the bare minimum. See 110.26 [408.18]. Also note that the bare minimum for Code compliance may not be the optimum distance for lowest total cost of ownership. Use sound engineering judgment, accounting for specific maintenance needs and other issues.That depehes. [408.5 and Table 408.5].
  5. They must be located such that the probability of damage from equipment or processes is reduced to a minimum [408.20].

 

 

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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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