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National Electrical Code

The NEC and Optical Fiber Cables

Dec. 15, 2020

A summary of Art. 770 Parts I through V

Part I of Art. 770 of the National Electrical Code (NEC) provides the general requirements for optical fiber cables. Although these are not current-carrying conductors, how and where you install them can affect “the practical safeguarding of persons and property from hazards arising from the use of electricity” [90.1].

Part I includes the usual requirements for cables, such as not blocking ceiling access [770.21], mechanical execution of work [770.24], removing the accessible portion of abandoned cables [770.25], and installing in such a way as to not substantially increase the spread of fire [770.26].

Part II provides requirements for cables that enter buildings, which are:

Overhead, including clearances and attachment limitations.
Underground, including those bundled with various kinds of current-carrying conductors and those that are unlisted.

Part III provides requirements for grounding, bonding, or interrupting cables, depending on whether they enter a building or terminate outside it.

Part IV provides extensive detail on how these cables should be grounded. Always ensure the fiber optic cable system grounding electrode is bonded to the power grounding electrode system [770.100(D)].

Part V covers installation methods within buildings.

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.