National Electrical Code

NEC Rules for X-Ray Equipment

May 21, 2019

Generating X-rays requires high voltage, and Art. 660 requirements mostly address that hazard.

Article 660 in the 2017 National Electrical Code (NEC) provides the requirements for X-ray equipment. Exposure concerns have greatly diminished with the widespread adoption of digital X-ray machines, which produce much less radiation than their older film counterparts. So, the beam is less of a problem than it used to be. But Art. 660 is not about the beam [Sec. 660.1]. Generating X-rays still requires high voltage, and the Art. 660 requirements mostly address that hazard.

Some highlights from this section of the Code include:

All high-voltage parts must be mounted within grounded (bonded) enclosures [Sec. 660.47(A)].
The disconnecting means must have adequate capacity for at least 50% of the input required for the momentary rating, or 100% of the input required for the long-time rating, whichever is greater [Sec. 660.5].
The ampacity of the branch circuit conductors must meet that same 50/100 requirement [Sec. 660.6(A)].
Feeder conductors supplying two or more X-ray branch circuits must comply with Sec. 660.6(B).
Low-voltage cables that connect to oil-filled units that aren’t completely sealed must be of the oil-resistant type [Sec. 660.47(B)].
Non-current-carrying metal parts must be grounded (bonded) per Art. 250 [Sec. 660.47(C)].

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.