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National Electrical Code Articles and Information

NEC Quiz: Article 356 Answers

by Mark Lamendola

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  1. In the prelude to the questions, we gave away the fact this is a nonmetallic conduit. We also gave away "it's a conduit" in this question. What we didn't give away is the particular type. This is Liquidtight Flexible Nonmetallic Conduit (Type LFNC) [356.1, 356.2].

    LFNC is a flexible nonmetallic conduit of circular cross section. It can be one of the three types enumerated in 356.2.

  2. Article 356 lists seven permitted uses [356.10]. Basically, you're going to use it where you would otherwise use a flexible metallic raceway but corrosion is a limiting factor. That's why, for example, you might use it for a motor that's sitting under a paper machine or in a pulping operation. It is suitable for direct burial, if it's listed and marked for that purpose.

  3. Article 356 lists four prohibited uses [356.12].

    One of those is in hazardous locations; that's because plastic and static electricity tend to be ready playmates.

    A second is for the protection of the conduit itself (where exposed).

    A third is in lengths greater than 6 ft. But you can exceed this if you can show the AHJ the greater length is necessary or if it's secured at intervals of 3 ft within 12 inches of every box, cabinet, and fitting.


  4. You must install Type LFNC using approved methods. Article 356 gives explicit commentary regarding bending, bend radii, number of bends, trimming, supporting, securing, and other facets of installation [356.24 - 356.42].

  5. You can use only fittings that are listed for use with LFNC [356.42]. And you can't use angled connectors for concealed raceway installations.



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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