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National Electrical Code Articles and Information

NEC Quiz: Article 374 Answers

by Mark Lamendola

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  1. In the prelude to the questions, we gave away the fact this is cellular metal floor raceway. What we didn't give away is the detail that tells you its defining characteristics. Basically, each cell is a tubular space in an array of cells (called a cellular metal floor member). It's a system, and you use metal fittings to connect the cells. Also, that row created by the arrangement of cells is parallel to the direction of the floor member. Wires also must run vertically (to get into the raceway), and for that purpose you use a header [374.1, 374.2].
     

  2. The NEC does not provide a list of "Uses Permitted" for this wiring method. Article 374 is arranged differently from the wiring method Articles that precede Article 372 (which also lacks this list) in chapter order. There's no subsection 10 (Uses Permitted) and what normally appears in subsection 12 is instead in subsection 3.

  3. You can't use it in hazardous locations or where subject to corrosion. In commercial garages, you can use the concrete version (Article 372) but those places are off limits to this metallic version. [374.3].


  4. There's no 374.30, either. That's because the raceway support is inherent. For the same reason, you don't provide supports for the 2x4 wall studs in a stick frame building when you use them to form the raceway; they are the supports.
     
  5. You must use "suitable fittings" [374.2]. Notice here that the NEC does not say "suitable metal fittings" as it does with the concrete version of Article 372. Probably, that omission is because adding "metal" is redundant. Connections to cabinets and other enclosures and/or to extensions from other cells must be made with listed metal raceways and listed fittings [374.11].

 

 

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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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