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National Electrical Code Articles and Information

Based on the 2014 NEC

by Mark Lamendola

National Electrical Code Tips: Article 690 -- Solar Photovoltaic Systems, Part 9

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. PV modules (other than ac current modules) are marked with several specifically required types of information, such as the polarity of the terminals (or leads). They are also marked with six ratings [690.51]. Before you install a module, read the markings to ensure it is actually the correct module for your application.
     
  2. Alternating current PV modules are also marked with several specifically required types of information. But instead of the six ratings, they are marked with five [690.52].
     
  3. Direct current PV power sources are marked with five ratings [690.53]; read the ratings before installing the module.
     
  4. You must mark all places where there's a point of interconnection between an interactive system point and any other source(s). The marking must be at an accessible point at the disconnecting means as a power source, with the rated ac output current and the nominal operating ac voltage [690.54].
     
  5. If the PV system has energy storage (e.g., batteries), mark the system with the maximum operating voltage, equalization voltage, and the polarity of the grounded circuit conductor [690.55].
     
  6. Any structure with a stand-alone (not connected to utility or other source) PV system must have a permanent directory or plaque installed on its exterior [690.56(A)]. The purpose of this is to inform first responders that there's an energy source and to inform them where the disconnect is.
     
  7. To the preceding point, you also need that plaque if the PV system disconnect isn't located where the service is located [690.56(B)].
     
  8. If the structure has "Rapid Shutdown," you must install a plaque or directory saying so [690.56(C)].
     
  9. If a load disconnect has multiple sources of power, the disconnect must disconnect all of them when in the OFF position [690.57].
     
  10. If you have an interactive system, you can use only inverters and ac modules listed as interactive [690.58]. One reason for this requirement is to ensure the inverter or ac module won't backfeed the utility during an outage; that's how utility workers get electrocuted, an experience that they don't exactly relish.

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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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