National Electrical Code

Intrinsically Safe Systems, Part 2

April 3, 2018

Do you know where to install intrinsically safe equipment?

Where can you install intrinsically safe equipment? Suppose you bought intrinsically safe equipment for a Class II, Division 1 location. That project turned out so well that you want to buy more of that same equipment for use in a Class I, Division 2 location. Is anything stopping you?

Probably not. Most likely, that equipment is identified for use in both locations. However, it might not be so identified. You’ll need to check that. Make sure any intrinsically safe equipment is identified for the hazardous location in which you intend to use it [504.10(B)].

Do you also need an intrinsically safe enclosure for your intrinsically safe I/O modules (and wiring, etc.)? No, you can use a general-purpose enclosure [504.10(C)]. Because all the apparatus is incapable of igniting a flammable gas or vapor, further protection (via enclosure) is unnecessary.

However, make sure you properly bond that enclosure. For example, don’t rely on a concentric knockout for a bonding connection. And don’t try to make a connection through paint; that will introduce a resistance and thus create differences in potential.

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.