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National Electrical Code Top Ten Tips: Article 230 -- Services

by Mark Lamendola

Please note, we do quote from copyrighted material. While the NFPA does allow such quotes, it does so only for the purposes of education regarding the National Electrical Code. This article is not a substitute for the NEC.

These are the 10 NEC Article 230 items we deem most important, based on the pervasiveness of confusion and the potential costs of same.

  1. NEC Figure 230.1 graphically shows which parts of NEC Chapter 2 apply to the various parts of the power distribution system. This figure should be your "road map" to applying the requirements of NEC Chapter 2.
     
  2. NEC 230.2 addresses the issue of the number of services. It balances the need for being able to shut off the power (for fire fighting purposes) at a central point with the practical aspects of running 2000A or more through a single service, plus it addresses other concerns. One item that older Codes did not require is a plaque showing the location of each service in a multi-service facility—and that such a plaque be posted at each service. It is wise to "retro-comply" with this Code requirement.
     
  3. NEC 230.10. "Vegetation such as trees shall not be used for support of overhead service conductors."
     
  4. NEC 230.24 discusses clearances. "Service drop conductors shall not be readily accessible…." (A) details the clearance above roofs, plus the exceptions. (B) details the clearance from ground, plus the exceptions. (C) and (D) refer to other Sections.
     
  5. 230.33 provides allows splicing or tapping of service-lateral conductors, if done per the several code Sections referenced.
     
  6. NEC 230.40. "Every service drop or lateral shall supply only one set of service-entrance conductors."
     
  7. NEC 230.42 says to size service entrance conductors for the "sum of the noncontinuous loads plus 125 percent of continuous loads." But, it allows you to size the service conductors for the "sum of the noncontinuous load plus the continuous load if the service-entrance conductors terminate in an overcurrent device where both the overcurrent device and its assembly are list for operation at 100 percent of their rating."
     
  8. NEC 230.43 limits the wiring methods to 16 specific types.
     
  9. NEC 230.82 limits the equipment you can connect to the supply side of the service disconnect to 7 specific items.
     
  10. NEC 230.90 covers overcurrent protection for service equipment. This contains important concepts that often don’t get implemented correctly. For example, "no overcurrent device shall be inserted into a grounded service conductor except a circuit breaker that simultaneously opens all conductors of the circuit."

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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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