Safety

NFPA 70E Tip: Informative Annex Q, Part 4

Sept. 20, 2019

This Annex is titled, “Human Performance and Workplace Electrical Safety.” It’s broken up into multiple parts (Q.1, Q.2, etc.).

Q4 is titled Human Performance Modes and Associated Errors. It covers three types of performance modes, as summarized below:

Rule-based performance mode. This mode generally follows the “If (symptom X) then (situation Y) logic. The most prevalent error for this mode is misinterpretation of the r
Knowledge-based performance mode. A worker operates in this mode when there is uncertainty about what to do. No skill or rule is readily identifiable. The prevalent error in this mode is decisions are based on an inaccurate mental picture of the work situation. Diagnosis and problem-solving are required, but these situation are often high-pressure ones in which people aren't at their best.
Skill-based performance mode. In this mode, the work requires practiced actions in a familiar and common situation. You might think this is ideal, since the mental load is so low (and thus what can possibly go wrong). But that's the problem, the mental load is low and this leads to inattention along with perceived reduction of risk.

Q4 provides more nuance and explanation than the summary presented here. A concentrated study of each of the subparts can help you gain new insights into reducing human error, especially if you examine the actual work performed as you go.

For example, a crew is going to replace a 400A breaker in a 480V panel. How much of that work is rule-based, and what are the possible sources of error? What are the knowledge-based and skill-based tasks in that job, and what are the possible sources of error for each?

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.