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National Electrical Code Articles and Information

Based on the 2011 NEC

by Mark Lamendola

National Electrical Code Top Ten Tips: Article 620, Elevators, Dumbwaiters, Escalators, Moving Walks, Platform Lifts, and Stairway Chair Lifts

  1. Article 620 is on the short list of NEC articles with the longest titles. It's really a catch-all for any kind of lifting device not covered by other Articles. It includes lifting devices for humans and lifting devices not for humans. Moving walks are tossed in there, too.
     
  2. Half of the dozen definitions in Article 620 pertain to elevators and dumbwaiters only. The other six definitions apply to all types of equipment covered by Article 620.
     
  3. Article 620 limits supply voltage to 300V between conductors [620.3], possibly under the theory that this voltage level is safe while 480V is not. We can't explain why this limit exists. But there are some exceptions permitted: lighting circuits, HVAC circuits, and certain kinds of power circuits.
     
  4. All live parts must be enclosed to protect against accidental contact [620.4]. This is already an Article 110 requirement, and the informational note for this section refers to 110.27.
     
  5. Working space must be provided [620.5]. This is already an Article 110 requirement, and 620.5 says the clearance cannot be less than that specified in 110.26. This suggests that 620.5 is emphasizing the idea that the work space be adequate, not that it meet some minimum in a chart and yet not be adequate for the worker to perform maintenance.
     
  6. All conductors must have flame-retardant insulation [620.11]. There are additional requirements for traveling cables and for hoistway door interlock wiring.
     
  7. When calculating ampacity, use Figure 620.13 to determine the applicable other Articles and which specific sections of Article 620 apply to that part of the system for which you are performing conductor ampacity calculations.
     
  8. Not all Chapter 3 wiring methods are allowed for this kind of equipment. In fact, there's a fairly short list of allowable raceway types [620.21].
     
  9. To size the overload protection for the motors in this equipment, follow Article 430 requirements, and rate the duty as intermittent [620.61].
     
  10. Part IX is titled "Grounding" and the language of the requirements says "bonding." Read the Article 100 definitions of grounding and bonding. It's very clear that you must bond. Grounding instead of bonding will result in an unsafe installation.

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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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