What is the process of blocking the flow of energy from an energy source to a piece of equipment, and keeping it blocked out?

• A. Lockout
• B. Tagout
• C. Grounding
• D. Interlock

Answer: (A)

Lockout is the process of isolating and securing a machine so that its energy sources are blocked from energizing the equipment. This means physically preventing re-energization by applying a lock (with a unique key) to the energy-isolating device and keeping that lock in place until maintenance is finished and the area is verified safe. The point is to provide a real barrier that stops unexpected startup or release of energy.

Tagout, by contrast, is a warning method that tags the equipment to indicate it should not be energized; it does not by itself physically block the energy source, so it is less protective on its own. Grounding channels electrical energy to the earth to reduce shock risk but does not isolate or keep equipment from being powered. An interlock prevents operation under certain conditions but isn’t the same as isolating and locking out energy sources.