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National Electrical Code Articles and Information

NEC Quiz: Article 100 Quiz, Part 3, Answers

by Mark Lamendola

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All answers are from Article 100.

1.   Continuous duty: operates at a substantially constant load for an indefinitely long time.
Intermittent duty:  operates alternatively between load and no load, load and rest, or a combination of the three.
Periodic duty: intermittent duty in which the load conditions regularly recur.
Short-time duty: operates at a substantially constant load for a time that is definite, short, and specified.
Varying duty: the loads and intervals of operation change.

2.   The definition isn't just a house or apartment--it's more inclusive than that. A dwelling is one or more rooms for the use of one or more persons as a housekeeping unit with space for eating, living, and sleeping and permanent provisions for cooking and sanitation.

3.   One-family, two-family, and multi-family.

4.   Many people confuse "energized" with "on" and "de-energized" with "off." That can literally be a fatal mistake. Something is "energized" any time it's connected to a source of power. A disconnecting means and a switch each serve different purposes.

5.   An explosion-proof device contains the flame of an explosion that occurs within it. It does not protect equipment from an explosion.

6.   Wiring is accessible if a qualified person can expose it without damaging the structure or finish of the building. Wiring is exposed if a person can touch it or approach it at an unsafe distance. Exposed wiring is, by definition, "not suitably guarded, insulated, or protected." Sometimes, you must expose wiring to work on it. That requires the wiring to be accessible. However, it should not be exposed when you are done working on it. It just needs to be accessible.

7.   A garage is a building or portion of a building in which one or more self-propelled vehicles can be kept for use, sale, storage, rental, repair, exhibition, or demonstration purposes.

8.  This rating is the highest current (at rated voltage) that a protection device is intended to interrupt under standard test conditions. Note: devices of the same interrupt rating may not be suitable for the same purpose.

9.   Labeled devices have a marking or label showing they have been tested to meet the criteria of the labeling authority.
Listed devices have also been tested, and are on a listóbut donít have the label to prove it.

10. Damp locations are protected from weather and saturation, but not moisture.
Dry locations are protected from weather, saturation, and moisture--or are normally not subject to them.
Wet locations are subject to saturation with water or other liquids.


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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