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621 Controlling Hazardous Energy (Lockout/Tagout)
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Step 2. De-Energize Equipment

To de-energize equipment, you must physically separate or isolate it from its energy sources with energy-isolating devices.

Energized/De-energized/Energized

Push Buttons and Switches

It's important to know that merely turning off equipment does not deenergize or separate it from its energy sources. Push-buttons, selector switches, safety interlocks, control circuit type devices, and programmable logic controllers (PLCs) used in many modern machine applications are NOT considered energy-isolation devices.

Energy Isolation Devices

On the other hand, energy isolating devices do physically prevent the transmission or release of energy. To physically separate or "isolate" the equipment from its energy sources after the equipment has been turned off, you must use energy-isolating devices.

Energy isolation devices may vary in design and configuration. The most common types are:

  • Circuit Breakers
  • Disconnects
  • Plugs
  • Valves
  • Flanges

Check out this great reference from DE energize that covers how to de-energize various types of energy.

Knowledge Check Choose the best answer for the question.

3-3. What does an energy-isolating device do?