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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 4

Part IV of Article 690 provides the requirements for wiring methods and materials. Nearly all of Part IV is about wiring methods. 690.31 has that heading, 690.31 is about component interconnections, and 690.34 is about access to boxes. 690.33 provides about a quarter page addressing mating connectors, the only "materials" covered by Part IV.

  1. You can use any wiring method in the NEC and any wiring systems and fittings specifically listed for PV systems [690.31(A)].
  2. PV system dc circuits and Class 1 remote control, signaling, and power-limited circuits of a PV system can occupy the same equipment wiring enclosure, cable, or raceway [690.31(B)].
  3. PV system dc cirucits shall not occupy the same equipment wiring enclosure, cable, or raceway as other non-PV systems, or inverter output circuits unless separated by a barrier or partition [690.31(B)]. The NEC does not explain the difference between a barrier and a partition, but since a partition is a type of barrier the question is moot. Excess verbiage (rather than clear and concise language) has long plagued the NEC. Overall, this problem is not as bad as it used to be; the CMPs have steadily been working on it.

  4. Identification is a really big deal with this revision. You must identify PV system conductors at all termination, connection, and splice points. The particulars are explained at length in 690.31(B)(1).
  5. What if you have more than one PV system and the conductors of those different systems occupy the same junction box or raceway? If the box or raceway has a removable cover, then you must group the conductors for each system using cable ties or similar means at least once every 6 feet [690.31(B)(2)].
  6. Can you put single-conductor PV cable in cable trays installed outdoors? Yes, if the cables are supported at intervals of 12 inches or less and secured at intervals of 4.5 feet or less [690.31(C)(2)].
  7. If your PV system dc circuits are inside a building and exceed 30V or 8A, they must be contained in metal raceways, Type MC metal-clad cable that complies with 250.118(10), or in metal enclosures [690.31(D)].
  8. Solidly grounded bipolar PV systems must be clearly marked with a permanent, warning legible notice indicating that the disconnection of the grounded conductor(s) may result in overvoltage on the equipment [690.31(E)].
  9. You can use concealed fittings and connectors for on-site interconnection of modules or other array components [690.32].
  10. Mating connectors shall be polarized and have a configuration that isn't interchangeable with receptacles in other electrical systems on the premises [690.33(A)]

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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