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National Electrical Code Articles and Information

Ten Tips on understanding the National Electrical Code

  1. You can see the National Electrical Code is laid it out in Articles and Chapters. Each Chapter contains related Articles. When making your way through the Code, think of the related topics you need to consider, then go to the Chapter that contains those topics. Inside that Chapter, you merely need to find the Article that addresses your topic.
  2. Article 90 is the introduction. It lays the foundation for understanding the National Electrical Code's scope and purpose, and where it fits into your work.
  3. Chapter 1, Article 100 covers definitions. Did you know Code experts often resolve National Electrical Code misunderstandings by simply using excerpts from Article 100? Become familiar with this Chapter, and you'll be ahead of the game. Try it!
  4. Chapter 2 covers wiring and protection, as well as grounding. Article 250 is "the grounding chapter." Article 210 covers branch circuits, Article 215 covers feeders, Article 220 covers calculations, Article 230 covers servicesódo you see the pattern, here?
  5. Chapters 2, 3, and 4 are where the typical electrician needs to focus--especially if studying for a National Electrical Code exam.
  6. Chapters 5, 6, 7 and 8 apply to nontypical applications, or specialized areas of electrical work. You don't need to study these for a National Electrical Code exam.
  7. Chapter 9 has your tables and examples. Spend some time becoming familiar with these and how to apply them!
  8. If you are doing non-specialized work, make a point of studying Chapters 1, 2, 3, and 4. Browse Chapter 9 to become familiar with what is in it, and work through the examples.
  9. For determining voltage drop and wiring sizes, work with Chapter 9, Tables 8 and 9--mostly Table 9 for a National Electrical Code exam.
  10. To make best use of the Tables in Chapter 9, read the "Notes to Tables" before working with the Tables. Itís amazing how many people end up going to these notes after hours of misusing the Tables.

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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