Test & Measurement

Tip of the Week: Read All Labels

Feb. 16, 2015

Read before you make measurements with your digital multimeter

So you’re the proud owner of a new digital multimeter (DMM). This one has a low impedance filter, a feature you’ve wanted for a long time. This means no more ghost readings! But do you know how to use your new DMM safely?

Between OSHA and NFPA 70E, you might think all the safety issues are covered. But what happens if you go to Panel 1017G instead of Panel 1007C? Both panels conform to the safety requirements employers must meet. Your particular DMM is rated for 1,000V. Panel 1007C contains 480V bus, so no problem there. But Panel 1017G is a medium-voltage panel. It contains a 4,160V bus.

Before you open any panel door, always read everything posted on the panel cover. Look for something that tells you what voltage level of equipment you can expect to find. If it’s not clearly marked, don’t open the panel. Find another way to verify the expected voltage.

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.