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National Electrical Code Articles and Information

Based on the 2017 NEC

by Mark Lamendola

National Electrical Code Top Ten Tips: Article 545, Manufactured Buildings

  1. Article 545 takes up less than a full page and is among the shortest of NEC articles. However, the manufactured buildings it covers are still subject to the first four Chapters of the NEC. Article 110 is especially important in this regard.
     
  2. Article 545 covers not just manufactured buildings, but also their components [545.1].
     
  3. You can use any raceway or cable wiring method in the NEC (those are listed in Chapter 3) and other wiring systems specifically intended and listed for use in manufactured buildings [545.2(A)].
     
  4. Closed construction is where the building or component is manufactured such that it isn't possible to inspect those after installation without disassembly, damage, or destruction [545.2].
     
  5. In closed construction, you can secure cables only at cabinets, boxes, or fittings where 10AWG or smaler conductors are used and protection against physical damage is provided [545.4(B)].
     
  6. You can't preinstall the service entrance conductors. They must be installed after erection at the building site [545.6]
     
  7. You must protect conductors during erection at the building site (and also during transit to the site) [545.8].
     
  8. Any box over 100 cubic inches in size and intended for mounting in closed construction must be affixed with anchors or clamps to provide a rigid and secure installation [545.9(B)].
     
  9. The manufacturer is required to make provision for bonding all prewired panels and building components; make sure you make the proper connections to the terminals or other bonding provisions [545.11].
     
  10. The manufacturer is required to make provision for routing a grounding electrode conductor from the supply to the point of attachment to the grounding electrode [545.12]. Do not confuse this with the bonding system; see the Article 100 definitions related to grounding and bonding.

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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