National Electrical Code Articles and Information

Code Quiz: Article 240

Based on the 2005 NEC

Questions and answers written by Mark Lamendola, who has worked as a master electrician, electrical inspector, and design engineer. Mark is an IEEE Senior Member, and the Code article author for Codebookcity.com. Since 1996, he has been writing National Electrical Code articles for electrical trade magazines and has an extensive portfolio of hundreds of NEC articles..

1. What is the minimum size OCPD (OverCurrent Protection Device) that must be installed on a fire pump?
    

2. Do specific applications have specific overcurrent protection requirements?
    

3. What are the two conditions permitted for purposes of electrical system coordination?
    

4. OCPDs must be protected in one of two ways. What are they?
    

5. Under what two conditions can you not use series ratings?

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.
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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.