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National Electrical Code Articles and Information

NEC Quiz: Article 336 Answers

by Mark Lamendola

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  1. It addresses Type TC power and control cable. This is a specific manufacture of cable. It's an assembly of two or more conductors under a nonmetallic jacket. The grounding conductor may be bare or covered [336.1, 336.2].

  2. Article 336 lists eight uses, and the seventh (in industrial establishments under specified conditions) has an exception. If you listed "in cable trays and in raceways," you got two of the eight. The first listed use is "For power, lighting, control, and signal circuits." This cable has many uses! Before you specify it for a job, however, look for it in the ampacity tables in Article 310. It's not there. That's because it's a low power cable, not a general conductor type.

  3. You can't use it where it's exposed to physical damage. Methods such as rigid conduit and intermediate conduit (Articles 342 and 342, respectively) fill this particular niche, but even in those cases you want to reduce the exposure as much as is practical.

    You can't install it outside a raceway or cable tray unless it's supported by messenger wire or under the special conditions described in 336.10(7) [336.2].

  4. Because it's a tray cable, it doesn't require its own support. If you use it outside of a tray or raceway, you must support it with a messenger wire [336.10(4)].

  5. You can use any terminations suitable for the conductors. The NEC says nothing on this aspect of installation.



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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