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National Electrical Code Articles and Information

NEC Quiz: Article 400 Answers (Part 2)

by Mark Lamendola

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  1. Types TPT and TST have their own column, because they come in 27AWG. That's referred to as tinsel cord. The 27AWG row of this Table is for those two types of conductors only. Notice it's empyt for the other two columns and the rows below the 27AWG row are empty for Types TPT and TST.

  2. If you compare the two tables, you see Table 400.5(A)(1) runs from 20AWG through 2AWG (plus it has that top row for two types of conductor that come in 27AWG only). but Table 400.5(A)(2) starts at 12AWG and runs to 1000 kcmil. It would be just silly to merge these two tables for that reason alone. Another factor (and there really are several but we'll stop at two) is that Table 400.5(A)(1) does not have three temperature columns (60, 75, and 90 DegrC) but Table 400.5(A)(2) does.

  3. It does matter. Use the adjustment factors in Table 400.5(A)(3) to modify the value(s) you obtained from Tables 400.5(A)(1) and/or 400.5(A)(2).


  4. Between an existing receptacle and an inlet, where the inlet provides power to an additional single receptacle outlet [400.7(A)(11)]
  5. Each flexible cord must be equipped with an attachment plug and energized from a receptacle or cord connector body [400.7(B)].

 

 

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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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