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National Electrical Code Articles and Information

NEC Quiz: Article 90 Answers

by Mark Lamendola

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1.      [90.1(A)]. In a word, safety. The NEC provides for the practical safeguarding of persons and property from hazards arising from the use of electricity.

2.      [90.1(B)]. This question misses the point of the NEC, which provides minimum standards for safety. The NEC is not a design guide, though it is a safety standard. With rare exceptions, the NEC does not address issues of convenience, efficiency, or adequacy for good service or future expansion. Failing to meet NEC requirements can carry serious criminal and/or civil consequences both to firms and to individuals.

3.      [90.1(C)]. No. The NEC is not an instruction manual for the untrained. The NEC makes no attempt to serve as a recipe book for those who don't have extensive electrical training. The NEC assumes the user already has this training. Consequently, people without this training have difficulty understanding much of what the NEC is even talking about.

4.      [90.2(A)(2)]. Yes. Parking lot lighting and other systems fall under the auspices of the NEC.

5.      [90.2(B)(1)]. No. Ships do not fall under the NEC. Shipboard systems are entirely different from land-based systems.

6.      [90.3]. The first four chapters apply generally—that is, they address all installations. Not all of the material in each of these chapters will apply to each installation. But something in each chapter will.

7.      [90.5 (A) and(B]).

Permissive rules identify actions that are allowed but not required. Mandatory rules identify actions that are specifically required or prohibited.

8.      [90.5(C)]. FPNs include such things as references to other standards, suggestions, and "FYI" material. FPNs do not contain Code requirements. The voltage drop information in [210.19(a) FPN No. 4 is an example of information many people falsely believe is a Code requirement.

9.      [90.7] If a product is Listed, you can install it without having it examined for approval for the applciation. This is a huge saver of time and money.

10. [90.9]. It uses both, depending on the trade practices and industry standards for a particular application.

 

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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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