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National Electrical Code Articles and Information

NEC Quiz: Article 424, Part 6 Answers

by Mark Lamendola

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  1. It applies to any heater mounted in the airstream of a forced-air system where the air-moving unit is not provided as an integral part of the equipment [424.57].

  2. Use with elevated inlet air temperatures [424.60], use with heat pumps and air conditioners and mounted closer than 4 ft to them[424.61], and use with air conditioners or other air-cooling equipment that could result in condensation [424.62]

  3. It has to be energized any time a heater circuit is energized. But a time or temperature controlled delay is permitted [424.63].

  4. It must be provided with an approved, integral, automatic-reset temperature-limiting control (or controllers) to deenergize the circuit(s) [424.64].
  5. Sufficient clearance must be maintained (this is an owner and occupant issue, not just an installer issue) to permit replacement of controls and heating elements, and for adjusting and cleaning as necessary [424.66].

 

 

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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