Test & Measurement

Tip of the Week: Insights from NEC Article 110, Part 2

Oct. 9, 2017

Make sure the equipment you’re installing is appropriate for specific applications.

The National Electrical Code (NEC) requires you to evaluate the equipment you’re installing to help ensure it’s appropriate for the specific application. Eight examination criteria are listed in Sec. 110.3(A)(1) through (8):

Suitability for the installation and use in conformity with the provisions of the NEC. Two Informational Notes help explain what is meant by this.
Mechanical strength and durability. Not just in general, but for the specific application. As an example, electrical tubing is very strong and durable, but you may need to step up to rigid conduit because of lift truck traffic in the area.
Wire-bending and connection space. Make sure you take into account the minimum bend radius of each conductor. Other kinds of wiring may have “excessive” need for space—some types of signal cables, for example. Figure all this out before mounting the box.
Electrical insulation. Is it suitable for the environment? THHN is widely used, but you want to run THHW in that damp location instead of THHN.
Heating effects under normal use. But also under abnormal conditions likely to arise in service.
Arcing effects. This includes a wide range of considerations for routing, spacing, bushings, and enclosures.
Classification by type, size, voltage, current capacity, and specific use.
Other factors that contribute to the practical safeguarding of persons using or likely to come in contact with the equipment. This “catch all” requirement is there because Code-making panel members can’t think of every possible issue. It’s up to the designer and installer to examine an installation for potential safety issues and mitigate or solve them.

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.