Test & Measurement

Tip of the Week: Insights from NEC Article 90, Part 3

July 31, 2017

This section of the National Electrical Code helps you determine which chapters of the code are the most relevant to specific job types.

Mark Lamendola

Many people take one look at the National Electrical Code (NEC) and their eyes glaze over. It’s so big that the 2017 looseleaf edition comes in a three-inch binder (8.5 x 11 pages).

The good news is you do not have to know, or even wade through, the entire NEC for a given project. That’s because of how the NEC is arranged. Figure 90.3 is a graphic that shows the breakdown:

Chapters 1 through 4. These apply generally to all electrical installations. But note that in Chapter 3, only four Articles (300, 310, 312, 314) apply generally. The other Articles (320 through 399) apply to specific wiring methods, so you just pick from those to match your wiring methods.
Chapters 5, 6, and 7. These supplement or modify the requirements in Chapters 1 through 4.
Chapter 8. This short chapter on communications systems is not subject to the requirements of the first 7, except where specifically referenced.
Chapter 9. Here, you’ll find page after page of tables. A given table applies only as referenced in the preceding chapters.
Informative Annex A through J. This is a valuable information resource, but it doesn’t contain any requirements.

The portion up to Chapter 5 is less than half the total page count. If you want to become more NEC-proficient, set aside a specific time each week to read and understand the Articles that apply to the work you do (start with Art. 100).

About the Author

Mark Lamendola

Mark is an expert in maintenance management, having racked up an impressive track record during his time working in the field. He also has extensive knowledge of, and practical expertise with, the National Electrical Code (NEC). Through his consulting business, he provides articles and training materials on electrical topics, specializing in making difficult subjects easy to understand and focusing on the practical aspects of electrical work.

Prior to starting his own business, Mark served as the Technical Editor on EC&M for six years, worked three years in nuclear maintenance, six years as a contract project engineer/project manager, three years as a systems engineer, and three years in plant maintenance management.

Mark earned an AAS degree from Rock Valley College, a BSEET from Columbia Pacific University, and an MBA from Lake Erie College. He’s also completed several related certifications over the years and even was formerly licensed as a Master Electrician. He is a Senior Member of the IEEE and past Chairman of the Kansas City Chapters of both the IEEE and the IEEE Computer Society. Mark also served as the program director for, a board member of, and webmaster of, the Midwest Chapter of the 7x24 Exchange. He has also held memberships with the following organizations: NETA, NFPA, International Association of Webmasters, and Institute of Certified Professional Managers.