Test & Measurement

Tip of the Week: The Basics of Chapter 9 in NFPA 70 (NEC)

March 7, 2016

The many tables provided in this Chapter offer lots of valuable information.

The first four Chapters of the NEC apply to all installations, except as modified by Chapters 5, 6, 7, and 8. Chapter 9 doesn’t modify anything. So why is it there and what use is it to you?

This Chapter provides useful tables. Lots of them. The amount of information contained here is staggering, and it’s amazing that the CMPs have, over the years, managed to keep these tables organized in a way that lets you easily page through them to find a table that applies to what you’re doing. The notes that go with these tables are informative, and they help you make sense of the data presented in each one.

These tables consist of three groups.

1) The first group of tables is all about conduit and tubing. Among other things, they help with determining bend dimensions and raceway fill.

2) The second group of tables is, logically enough, about conductors. If there’s a dimension or property you need to know for a given size of a given conductor, you’ll probably find it here.

3) The third group provides power source limitations for Class 2 and Class 3 power supplies and for the power supplies of Power Limited Fire Alarm (PLFA) systems.

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.