Ecmweb 8662 595thinkstockphotos 71261469
Ecmweb 8662 595thinkstockphotos 71261469
Ecmweb 8662 595thinkstockphotos 71261469
Ecmweb 8662 595thinkstockphotos 71261469
Ecmweb 8662 595thinkstockphotos 71261469

Tip of the Week: Run a Full Battery of Tests

Dec. 5, 2016
One test of your equipment might detect a problem, but to uncover all potential issues, you will need to conduct a full range of tests.

You’ve no doubt heard the expression, “If all you have is a hammer the whole world looks like a nail.” This expression also applies in maintenance and troubleshooting.

Credit: Purestock/Thinkstock

Maintenance electricians typically carry a digital multimeter (DMM) with them. Considering what a DMM can do, this makes great sense. But it also can trap them into thinking in that hammer-and-nail fashion.

Suppose a motor opens its overload strips. You replace those and use your DMM to verify the correct voltage. No low voltage or voltage imbalance here, so it’s all fixed now!

But the motor can be vibrating. You don’t have a vibration tester with you, so should you check this? Absolutely. And you should use a higher-end tester so you can tell what’s going on other than “lots of vibration.” The meter should tell you the velocity, displacement, and acceleration. Even before using this instrument, you should put your DMM away and visually inspect the motor base and pedestal.

Vibration is only one of many potential causes your DMM isn’t going to detect. And it is not even a root cause; you will need other test equipment to prove and correct a root cause such as a misaligned load.

That vibration tester might not help you do anything other than eliminate vibration as a cause. What other tests might you perform? What about any or all of the following?

Thermographic scan of the motor and of its immediate environs. A nearby heat source might be the culprit.

Harmonic analysis of the branch-circuit and/or feeder supplying the motor. Good thing you found that big 5th harmonic!

Power quality analysis of that circuit. Hmm, that flat-top does not look like a healthy sine wave.

Bearing temperature measurements. If you fix other problems but don’t detect hot bearings, how are you going to look the next day when they fail?

Ultrasonic analysis. This will reveal impending bearing failure and/or other problems.

Insulation resistance tests. Is the insulation on those windings OK?

Although the DMM is indispensable, you need to be thinking of what tests you can perform to diagnose the problem rather than what tests your DMM can perform. If you’re troubleshooting critical equipment, good methodology requires running a full battery of tests. If you stop when you “find the problem” you may be stopping only when you find one of two problems.

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.

Voice your opinion!

To join the conversation, and become an exclusive member of EC&M, create an account today!

Sponsored Recommendations

Electrical Conduit Comparison Chart

CHAMPION FIBERGLASS electrical conduit is a lightweight, durable option that provides lasting savings when compared to other materials. Compare electrical conduit types including...

Don't Let Burn-Through Threaten Another Data Center or Utility Project

Get the No Burn-Through Elbow eGuide to learn many reasons why Champion Fiberglass elbows will enhance your data center and utility projects today.

Considerations for Direct Burial Conduit

Installation type plays a key role in the type of conduit selected for electrical systems in industrial construction projects. Above ground, below ground, direct buried, encased...

How to Calculate Labor Costs

Most important to accurately estimating labor costs is knowing the approximate hours required for project completion. Learn how to calculate electrical labor cost.