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National Electrical Code Articles and Information

NEC Quiz: Article 300, Part 5 Answers

by Mark Lamendola

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  1. [300.13(A)]. Generally, you can't leave a splice in a raceway. But there are a few exceptions, such as 300.15. Even where permitted, it's best not to do it simply from an engineering and maintenance standpoint.
     

  2. [300.13(B)]. The pigtail. You can't let the terminals of a device become a means of disconnecting the neutral. In all other types of circuits, pigtailing isn't required but it's a good practice. If you always pigtail the neutral, then you never disconnect it by simply removing a device from the circuit.
     

  3. [300.16]. This is a common point of misunderstanding. The rule exists to allow an electrician to be able to work with the wiring. There are actually 2 minimum lengths. Normally, you must leave at least 6 inches of wire from the point where the wire enters the box. If the box is less than 8 inches in any dimension, each conductor must be long enough to stick out of the box with 3 inches left over.

    How much is too long? The NEC does not say. You can always cut a wire twice to make it shorter, but you can't cut it twice to make it longer. If in doubt, leave it (hanging) out.
     

  4. [300.18)B)]. Generally, no. And if your boss finds out you've been wasting time this way, you'll probably be fired. However, there are special circumstances in which welding is permitted by the NEC and is actually appropriate in all other concerns. These are covered in application-specific Articles.
     

  5. [Table 300.19]. Yes. Use this table to sort out what's what.

 

 

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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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