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Test & Measurement

Tip of the Week: Motors and Moisture, Part 1

July 17, 2017

Don't try to remove moisture from a motor by running it; that can lead to damage.

Excessive moisture can cause a motor to run hot. This is because the moisture penetrates the insulation material and degrades its insulating properties. The moisture creates parallel leakage current paths through and over the surface of the insulation.

If you suspect or detect moisture, don’t run the motor under the assumption that doing so will dry out the motor, the problem will solve itself, and everything will be fine. Running a moist motor stresses the motor, and often damages its insulation.

If you think the problem is due to moisture, you need to dry out the motor without running it.

To prevent recurrence, you may need to do some serious troubleshooting. But at a minimum, at least look for obvious causes; in most cases, doing so will enable you to solve the problem permanently.

For example, a motor is in a damp location and runs infrequently, so condensation forms once the motor cools. A common solution is to install a heater that dries out the windings.

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.