How to Understand National Electrical Codes

Electricians in the United States adhere to the National Electric Code for guidelines on installing electrical equipment.

The National Electric Code (NEC) contains the standard rules and regulations in the United States for installation and modification of electrical wiring. The NEC is part of the National Fire Codes and is published by the National Fire Protection Association. The National Electric Code is not a U.S. federal law, it is commonly part of state or local law. The NEC may be difficult to decipher for individuals new to its use, but most electricians quickly become adept at understanding the code.

Things You'll Need

• 2011 National Electric Code (NEC) book

Instructions

1. Read Article 90 first. Article 90 is the introduction to the NEC, and contains valuable information about the scope of the codes and their purpose. If you have questions on the purpose of the NEC or how your work involves the code, Article 90 contains the answers.

2. Consult Article 100 in Chapter 1 to familiarize yourself with definitions often used in electrical wiring and throughout the NEC. Refer back to Article 100 at any point when reading the codes if you are unsure about specific terms or word use. This prevents misunderstandings based on definitions.

3. Familiarize yourself with the format of the NEC. The NEC is structured in chapters that contain related articles. For any topics you research in the NEC, first locate the chapter that matches your topic and then peruse the assorted articles. Chapter 1 contains information on the NEC and definitions. Chapters 2, 3 and 4 cover the basic information used by the typical electrician. Chapters 5, 6, 7 and 8 contain information on atypical situations and specialized areas of electrical work.

4. Read the "Notes to Tables" section in Chapter 9 if you need to use the tables in the NEC. This section describes functionality of the tables, including how you should interpret and apply them.

Tips & Warnings

• The code can be accessed for free online in lieu of purchasing a paper copy every three years. Access the online copy at bulk.resource.org/codes.gov/.

• The NEC is updated and re-published once every three years. Make sure that the copy you use is the most current copy at the risk of working from outdated information. Local codes may take longer to update after publication of the new NEC, but you should always use the most current code.

References

• "National Electric Code 2011 Handbook"; National Fire Protection Association; 2010.
• "Interpreting the National Electric Code"; Truman Surbrook; 2008.

Resources

• Bulk Resource: Parent Directory