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National Electrical Code Articles and Information

Based on the 2011 NEC

by Mark Lamendola

National Electrical Code Tips: Article 690 -- Solar Photovoltaic Systems, Part 7

Only about 15% to 20% of the work of installing a Solar Photovoltaic (PV) System is electrical. But that electrical portion can easily result in disaster if not done correctly. Thus, Article 690 provides requirements for that portion.

  1. You must provide a means of disconnecting all current-carrying conductors of a PV system from all other conductors in the structure [690.13].
     
  2. The disconnecting means can be a switch, breaker, or other device. Just make sure if it disconnects the grounded conductor, it doesn't leave the marked, grounded conductor ungrounded and energized [690.1]. There are a couple of exceptions to this rule.
     
  3. The PV system disconnect does not have to be suitable as service equipment, but it must comply with the several requirements spelled out in 690.17.
     
  4. You can place the disconnect inside or outside the structure, but it must be readily accessible and near the point of entrance of the conductors [690.14(C)(1)].
     
  5. Permanently mark the disconnect to identify it as the system disconnect [690.14(C)(2)]. This way, first responders can see where to disconnect the power.
     
  6. Though each disconnect itself doesn't have to be suitable as service equipment, the service equipment rules apply generally. For example, you can't have more than six disconnects 690.14(C)(4)] and they must be grouped [690.14(C)(5)].
     
  7. While the disconnects have to be readily accessible, the inverters do not. You can mount those on the roof, if you want to [690.14(D)].
     
  8. If you install fuses, provide a means to disconnect them from all sources of supply 690.16(A)].
     
  9. What wiring methods can you use? All that are included in the NEC and other wiring systems (and fittings) specifically intended and identified for PV systems [690.31(A)]. You must install those per the relevant NEC requirements. For example, install flexible cord per Article 400 [690.31(D)].
     
  10. For on-site interconnections of modules, you can use fittings and connectors that are intended to be concealed. But they must be listed for such use and must be at least equal to the wiring methods used [690.32].
     

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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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