Article 250 of the National Electrical Code (NEC) is arguably the most difficult Chapter 2 article to understand and correctly apply. One reason is that people often approach it without knowing the difference between grounding and bonding. If you read the definitions in Art. 100, you will see that grounding means you connect it to the earth, and bonding means you create a metallic path back to the source. With this in mind, you can see that driving a ground rod next to a motor simply wastes a ground rod.
Another reason people get confused and end up with unsafe installations is this notion that electricity takes the path of least resistance. Is this true? On paper, draw a simple circuit with two resistors in parallel. One is 100 Ω, the other is 500 Ω. Do you think all of the electricity flows through the 100-Ω resistor? If you solve each parallel branch for current, you will see that five-sixths of it flows through the 100- Ω resistor, and one-sixth through the 500-Ω resistor.
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.