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National Electrical Code Articles and Information

NEC Quiz: Article 440 Answers

by Mark Lamendola

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  1. Because EMT uses compresion-style fittings, you must run an EGC of the wire type within the EMT [440.9].

  2. The ampere rating of the disconnect for a hermetic compressor motor must be at least 115% of the nameplate rated-load current or the branch-circuit selection current (whichever is greater) [440.12(A)(1)].

  3. Locating it on the panel is almost certainly the worse choice in all circumstances. And if the panel in question is an acess panel, locating it there is prohibited [440.12(B)(1)].

  4. Its ampacity must be sufficient for all of the loads you intend for it to carry [440.34]. Be sure to refer to 440.32 or 440.33, for single compressor-motor applications and multiple motor applications, respectively. For example, if you are installing a residential heat pump that also has a 15A convenience receptacle on the same supply conductors then you would size the heat pump part per 440.33 because you have the compressor motor and the fan motor (more than one motor) on those conductors.

  5. Yes, in fact you are required to. The OCPD must have sufficient time delay to permit starting the unit. Because these units often start under load, the delay may be considerable.



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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