Electrical Troubleshooting Quiz — Jan. 5, 2021
You have an interview with the plant engineer for the newly created position of electrical maintenance manager. The plant engineer is asking the usual questions per some interview guide from HR. You stop him and ask if he can describe a problem the plant is having. “Maybe one that keeps you up at night,” you add.
He nods and starts telling you about the bad connection problem. Three years ago, he hired a thermographer to begin an annual survey to identify bad connections. After getting the results, he assigned one of the electricians to tighten all of those connections. The thermographer came back a year later, and all of those connections were bad, and many others were newly bad.
The following year, he hired a different thermographer and got even worse results. What is causing this?
First, explain that tightening a connection only makes it worse. That’s why the thermography results keep getting worse, and the same connections keep showing hot. The steel of the bolt or screw stretches when you tighten it, thus providing the clamping force. Once you loosen that fastener, tightening it to that torque provides a significantly lower force. The stretching is a permanent deformation, so a proper repair includes replacing the fastener (e.g., bolt) and any locking devices (e.g., lockwasher).
Ask him to pick any 10 connections, perform a thermographic scan, repair only the ones with a high resistivity using new hardware torqued per the manufacturer’s recommendations, and scan those again. Don’t be surprised if you get the job offer after that’s done.
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.