Test & Measurement

Tip of the Week: The Basics of Chapter 3 in NFPA 70 (NEC)

Sept. 21, 2015

Chapter 3 spells out the requirements for wiring methods and materials.

The first four Chapters of the NEC apply to all installations, except as modified by Chapters 5, 6, 7, and 8. The requirements for wiring methods and materials are in Chapter 3.

Article 300 provides the basis for understanding and applying the Articles that follow it in this Chapter. With the 2014 NEC, the scope of Art. 300 was amended to include the “and materials” part.

What’s meant by “methods and materials” is the “stuff” you use to do the wiring. This includes conductors, raceways, boxes, fittings, cables, cable trays, and busways.

The Articles in Chapter 3 are grouped thematically. That is, you’ll find a sequence of them for tubing, a sequence for conduit, a sequence for cable types, and so on. This logical arrangement of “like things” being grouped together makes the Code easier to use. With Chapter 3, the grouping approach is especially helpful because there are so many wiring methods.

What if you want to use a wiring method that, despite its scope, Chapter 3 does not include? Only wiring methods recognized as suitable can be used [110.8]. Except as modified by Chapters 5 through 8 (and particularly Chapter 8), the recognized wiring methods are in Chapter 3.

Many of the Chapters include a subsection 10 “Uses Permitted” and subsection 12 “Uses Not Permitted.” This arrangement helps you efficiently and correctly decide on the proper wiring method for a specific application.

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.