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National Electrical Code Articles and Information

Based on the 2005 NEC

by Mark Lamendola

National Electrical Code Top Ten Tips: Article 527, Temporary Installations

(This Article was discontinued with the 2008 NEC, so it appears only in the 2005 NEC and earlier.)

Arnold terminated villains and good guys alike, in his three Terminator movies. However, death and destruction should not be the role of your temporary installations--whether to your reputation or to people on the site. Here are 10 tips to make sure they aren't. 

  1. Note that the electrical inspector isn't the only Authority Having Jurisdiction (AHJ) for an installation, especially while it is in progress and there is temporary power or light. Others who can enforce the codes are the general contractor, OSHA, insurance providers, other trades, and the property owner [527.1].

  2. Article 527 applies to all temporary power and lighting installations, including power for construction, remodeling, maintenance, repair, demolitions, and decorative lighting. Follow it for those installations to prevent liability issues.

  3. Article 527 also applies when emergencies or testing require temporary installations. All of the requirements of the NEC apply to temporary installations unless specifically modified in Article 527. There aren't many such modifications.

  4. Specific venues have additional requirements--for example, trade shows must comply with Article 518.

  5. Don't install temporary wiring on a permanent basis. The time constraints are very clear, and they are legally enforceable in both civil and criminal courts. You must remove all temporary installations when you have completed the work that required installing them.

  6. In 527.4, you'll find specific rules for each major area of application. This is laid out very logically, so there is no mystery as to what is expected of you.

  7. You must install a temporary service per Article 230. That's right--the permanent rules apply, even to temporary services.

  8. Temporary feeder installations do not permit the use of open conductors, unless the individual open conductors are accessible only to qualified personnel. Don't abuse the "qualified personnel" idea. OSHA is very clear on what this means. If you can't document training for the specific tasks required, then you don't have qualified personnel. Just being an electrician, no matter how good, does not make someone a "qualified person."

  9. Contrary to established myth, all ungrounded circuit conductors must have a disconnecting means. That doesn't mean a taped-up splice. It means a switch, disconnect, or other device rated for the application. From a safety standpoint, it's even more important to have a highly visible, readily accessible disconnect for temporary installations than it is for permanent installations. The reason why is obvious to anyone walking through a construction site.

  10. Think of temporary installations as just that. The advantage of them is they generally allow you to use cords and cable assemblies rather than installing raceways, and they allow you to place splices outside of boxes. But, they don't allow you to to do that without a small price. You must also provide the additional protection of a GFCI and/or grounding program (e.g., AEGCP). Don't worry so much about satisfying the AHJ. Worry about ensuring your own safety by making your temporary installation conform to Article 527.


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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