Electrical Troubleshooting Quiz — June 19, 2018
A fault on a branch circuit resulted in tripping the 1,200A feeder breaker, but the 200A branch circuit breaker did not trip. The 200A breaker was replaced with a new one.
One of the maintenance electricians suggested there might be a problem with the 1,200A breaker. Since the 200A one has already been pulled, testing it first won’t incur any downtime. So, he suggested sending the 200A breaker out for testing, to rule it out as the culprit.
Thus, the breaker was sent to a local electrical shop that just happened to own a breaker testing device. Various levels of overcurrent were used to test the breaker, and it opened each time. Should you send the shop the 1,200A breaker to see what it does?
The response to this situation indicates a breaker coordination study has not been performed. That’s a bigger issue than simply solving this one conflict.
Determine the time delay of each breaker. Then have that electrical shop test the 200A one against the specified time delay, not just whether the breaker trips. The 200A breaker might have responded slowly due to poor maintenance (e.g., improper cleaning and lubrication). What is the maintenance history of that breaker? If there isn’t any, that is also a bigger issue.
Check the bonding connections of that 200A circuit. And if you have either of the other two problems, contact a qualified firm for help.
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.