Electrical Troubleshooting Quiz — May 5, 2020
This morning, the office manager who oversees the plant’s 4-story administration building phoned the electrical maintenance manager to say the offices have quite a few dead receptacles. These are all 120V, and the office manager personally checked the distribution panel on each floor for breakers that were off and did not find any.
The electrical maintenance manager described what the breaker trip indicator was. He then asked the office manager to make sure he was wearing safety glasses and to look again at those panels, but simply report back. Two of these breakers were tripped, but this does not account for all the dead receptacles.
How can you methodically and efficiently determine where and what the problems are?
Conduct a load assessment on one of the two breakers that tripped. Ask what can stay unplugged and reduce total load to below 80%. Then, open and close the breaker. Next, measure power at each receptacle on that circuit. Repeat the same process for the other breaker.
On one that did not trip, repeat the load assessment/unplugging. Then open and close the breaker. Now, measure power at the first receptacle on the circuit. If there is no power, open the breaker, remove the receptacle, connect your DMM to the supply wires, and radio your helper to close the breaker. If there is no power, ask your helper to measure on the breaker load side; if no power there, replace the breaker. If you have power at the breaker, this indicates a wiring failure. If you have power at the receptacle supply, measure on the load side. If power is present there, go to the next receptacle. Repeat this tracing.
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.