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National Electrical Code Articles and Information

NEC Quiz: Article 338 Answers

by Mark Lamendola

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  1. It addresses Type SE and USE cable. The designation "SE" stands for Service Entrance. The "U" is for Underground. [338.1, 338.2].

  2. Article 338 lists two uses. Obviously, it can be used as a service-entrance conductor. But (if you don't mind the expense) you can also use it for branch or feeder circuit conductors [338.10] if you meet certain requirements in the installation.

  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 underground unless it's USE, regardless of whether you enclose it in a raceway. You can't use it for outdoor branch or feeder wiring unless the installation complies with Article 225 and you provide support per 334.30 (or as messenger-supported wiring per Part III of Article 396) [338.12(A)].

    Further, there are restrictions on where you can use USE: interior wiring; above ground installations (except where the cable emerges from underground and it has to be terminated there); as aerial cable, unless the installation meets specified conditions [338.12(B)].

  4. For aerial installations, you can use a messenger wire. Otherwise, you can use any hardware suitable to the application and to the size cable you are using. Whatever you do, don't exceed the bend radius [338.24].

  5. Article 338 doesn't specify the types of terminations to be used. But as the typical use of this cable means a large conductor, you should use a power crimping tool with the correct compression dies, being sure you use lugs that match the cable. And that is after you use the proper tools to correctly remove the insulation (a pocketknife is not correct).

    If you haven't been specifically trained in preparing and terminating large service conductors, you're not a qualified person. Leave the job to someone who knows what they're doing.



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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