Maintenance, Repair & Operations

Unsafe Conditions Around De-Energized Equipment, Part 2

April 16, 2019

Ensure all sources are de-energized, not just electrical ones.

You reviewed the electrical drawings and locked out every relevant breaker and disconnect. Per your company’s electrical safety procedures, this equipment is now de-energized. But is it really?

Suppose the ram on a large press has stopped at the top position. In this position, the ram is storing a dangerous amount of kinetic energy. To deenergize the ram, you can lower it to its bottom position. If doing so isn’t practical, you must block the ram with the appropriate devices so it can’t possibly release that energy while you’re working.

Mechanical springs also store energy. Suppose you’re repairing a machine that cuts plastic strips. The blade mechanism has a spring return, so the blades are normally “armed” and ready to chop fingers. If you disengage the spring, you remove the stored energy.

Capacitors, batteries, gas cylinders, hydraulic cylinders, and pneumatic cylinders also store energy. Ensure all sources are de-energized, not just electrical ones.

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.