Maintenance, Repair & Operations

Information Technology Equipment

March 17, 2020

A brief overview of Article 645 of the 2020 NEC

Article 645 of the 2020 National Electrical Code (NEC) covers equipment, power supply wiring, equipment interconnecting wiring, and grounding (bonding) of information technology (IT) equipment and systems in IT equipment rooms.

Many other Articles/Sections apply to these rooms [645.3(A) through (I)]. For example, the non-current-carrying conductive members of optical fiber cables within such a room must be bonded per Sec. 770.14 [Sec. 645.3(C)]. And you’ll find Sections of half a dozen other Articles referenced in Sec. 645.3(B)(1) through (6).

You can use Art. 645’s wiring methods instead of the wiring methods of Chapter 3 and Parts I and V of Art. 770, but only if you meet the conditions listed in Sec. 645.4(1) through (6).

Branch circuits supplying one or more units of IT equipment must have an ampacity of at least 125% of the total connected loads. If you run branch circuit supply conductors under a raised floor, you must install them per Sec. 300.11. You must also use the wiring methods of Sec. 300.22(C) and/or the 17 wiring methods listed in Sec. 645.5(E)(1)(b)(1) through (17).

Overcurrent protective devices (OCPDs) supplying critical systems must be selectively coordinated [Sec. 645.27] with all supply side OCPDs.

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.