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Safety

NFPA 70E: Annex Marks the Spot — Part 10

Jan. 17, 2025

Informative Annex K provides some general — yet important to understand — information about electrical hazards.

This Annex consists of K.1 through K.5. The first paragraph of K.1 provides some statistics from the U.S. Bureau of Labor Statistics (BLS). As they cover 1992 through 2012, they are a bit outdated, and they don’t show you injuries per thousand workers or some other relational figure. Yet they give you an idea of how to assess your own company’s electrical injury history. How many electrical injuries per labor hour has it had each year since 10 years ago? Is the trend upward (not good) or downward (good)? What can you do to improve this?

The rest of K.1 provides insights such as:

Electric shock and electrical burns are the two general categories of electrical injury.
About 98% of fatal occupational electrical injuries are electric shock injuries.
The highest proportion of electrical fatalities are in shops with 10 or fewer people.

K.2 provides statistics on electric shock. For example, over 40% of all electrical fatalities in the United States involve overhead power line contact. K.3 provides statistics on arc flash, with OSHA as the source. For example, OSHA estimates that an average of at least eight burn injuries from arcs occur each year involving employees covered by OSHA rules. K.4 provides numerical descriptions of arc blast effects. For example, copper expands by a factor of 67,000 times when vaporized. Think of a copper connector taking up 67,000 times as much space!

Informative Annex K ends with K.5, which lists four documents you can obtain for more information.

The purpose of this Informative Annex isn’t to endow you with the exact, most recent figures on electrical hazard related injuries. It’s to help you see some of the magnitudes involved. Compliance with NFPA 70E and other safety standards, regulations, and programs is often hampered by the “It hasn’t happened here” perspective. Reading this annex helps people see that it has happened, even if not here yet — and it has happened a lot.

When “it” involves pressures of thousands of pounds per square foot and speeds so fast that molten metal can “completely penetrate the human body” any sense of triviality should evaporate.

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.