Test & Measurement

Tip of the Week: Understanding the Structure of Chapter 2 of the NEC

Aug. 24, 2015

The chapter provides the basis for wiring and protection.

The first four Chapters of the NEC apply to all installations, except as modified by the four Chapters that follow (5, 6, 7, 8). Chapter 2 provides the basis for wiring (but not wiring methods) and protection. It’s arranged into these groupings (not officially recognized as such in the NEC, but the arrangement exists):

Identifying and using grounded (not grounding) conductors. Article 200.
Rules by type of distribution (services, feeders, branch circuits), including load calculation. Articles 210, 215, 225, 230.
Overcurrent protection. Article 240. For services, also covered in Article 230, Part VII (yes, use the rules from both places).
Grounding and bonding. Article 250.
Transient protection. Articles 280 and 285.

It’s important to note that the requirements for grounded conductors aren’t in “the grounding and bonding Article” (250). This helps avoid confusion between the grounded conductors and grounding conductors:

A grounded conductor is a system or circuit conductor that is intentionally connected to the system “ground” (typically at the transformer or other source). A common example is the neutral wire. The neutral conductor is connected to the neutral point of a system, and that connection is what makes it the neutral. On systems 50V to 1,000V, the neutral is always grounded [250.20(B)]. But the grounded conductor isn’t necessarily the neutral in all systems, so don’t use these terms interchangeably.
A grounding conductor is one that connects something to the system ground. An example is the equipment grounding conductor, which connects normally non-current carrying metal parts of equipment together and to the system grounding conductor and/or the grounding electrode conductor.

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.