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Course 710 - Energy Control Program (Lockout/Tagout)

Safety guides and audits to make your job as a safety professional easier

Application of Energy Control Devices

Basic Steps in Controlling Energy

To control hazardous energy, you have to prevent it from being transmitted from its source to the equipment that it powers. You can accomplish this by doing the following:

  • identify energy sources;
  • de-energize equipment by isolating or blocking the energy sources;
  • dissipate potential (stored) energy that could affect the equipment;
  • lock out the equipment's energy-isolating device; and/or
  • tag out the energy-isolating device only if you can't lock it out.

To safely apply energy controls to machines or equipment (using either lockout or tagout devices), authorized workers must perform certain procedures, in a specific order.

Preparing for Shutdown

The first step in controlling energy is to identify equipment in your workplace that needs service or maintenance. Determine the form of energy that powers the equipment, including potential energy that may remain when the energy source is disconnected. Label the energy sources so that workers will know what equipment is powered by each energy source.

Before an authorized or affected employee turns off a machine or equipment, the authorized employee must have knowledge of the type and magnitude of the energy, the hazards of the energy to be controlled, and the method or means to control the energy.

Shutting Down Machinery or Equipment

The machine or equipment must be turned off or shut down using the procedures established for it to avoid any additional or increased hazards to workers as a result of the unexpected machine or equipment startup or stoppage.

Machine or equipment isolation: All energy-isolating devices that are needed to control the machine's energy source must be located. These devices must then be used to isolate the machine or equipment from its energy source(s).

De-energizing equipment means isolating it from its energy source and controlling potential energy so that no energy can flow to the equipment. The method you use to de-energize equipment depends on the form of energy and the means available to control it.

Below is a list of safe practices for de-energizing equipment.

  • Disconnecting motors from the equipment
  • Isolating electrical circuits
  • Disconnecting equipment from energy sources
  • Blocking the fluid flow in hydraulic, pneumatic, or steam systems with control valves or by capping or blanking the lines
  • Blocking equipment parts that could be moved by gravity

Stored energy must be released after equipment has been de-energized. Below is a list of possible sources of stored energy.

  • Capacitors
  • Coiled springs
  • Elevated machine members
  • Rotating fly wheels
  • Air, gas, steam, chemical, and water systems

If the energy could return to a hazardous level, make sure that it remains isolated from the equipment until all service work is finished. Below is a list of safe practices for dissipating potential energy.

  • Vent pressurized fluids until internal pressure levels reach atmospheric levels.
  • Discharge capacitors by grounding them.
  • Release or block tensioned springs.
  • Ensure that all moving parts have stopped completely.

Energy-Isolating Devices

Energy-isolating devices prevent energy from being transmitted from an energy source to equipment. Energy-isolating devices are the primary means for protecting those who service equipment. Examples of energy-isolation devices include:

  • manually operated electrical circuit breakers;
  • main disconnect switches;
  • line valves; and
  • blocks.

Applying Lockout/Tagout Devices

An energy-isolating device is effective only when no one can accidentally restart the equipment. Locking out is a procedure for securing an energy-isolating device in an off, closed, or neutral position. When an energy-isolating device is locked out, a worker can safely service hazardous equipment. A lockout device - typically a lock with a unique key or combination - secures the energy-isolating device in a safe position. When an energy-isolating device is locked out, the equipment it controls will not work until the lockout device is removed.

Similarly, tagging out is a procedure for placing a warning tag or sign - a tagout device - on an energy-isolating device. Remember, tagout devices must control hazardous energy at least as effectively as lockout devices. Since tagout devices do not provide the same physical barrier to hazardous energy as lockout devices, it is harder to ensure (or prove to OSHA) that tagout devices are as effective as lockout devices.

Bottom line: If you can lock it out, do not use tags.

Key Criteria When Applying Lockout/Tagout Devices

  • Lockout or tagout devices must be attached to each energy-isolating device by authorized workers.
  • Lockout devices, where used, must be attached in a manner that will hold the energy isolating devices in a "safe" or "off" position.
  • Where tagout devices are used, it must be attached in a manner that will clearly indicate that the operation or movement of energy isolating devices from the "safe" or "off" position is prohibited.
  • If the tag can not be attached directly to the energy isolating device, the tag must be located as close as safely possible to the device, in a position that will be immediately obvious to anyone attempting to operate the device.
  • A tagout device must be securely fastened to the energy-isolating device and must state that the equipment being serviced can't be operated until it is removed.

Lockout or tagout? How to decide

If you can lock out an energy-isolating device, then you must lock it out before you service the equipment that it controls. If you can't lock out an energy-isolating device, then you must tag it out. Remember that you must ensure that the hazardous energy is controlled just as effectively with the tagout device as it would be with a lockout device.

Releasing Stored Energy

After the energy-isolating device has been locked out or tagged out, all potentially hazardous stored or residual energy must be relieved, disconnected, restrained, and otherwise rendered safe.

Verifying Machinery or Equipment Isolation

Energy-Isolating Devices
(Click to enlarge)
Each authorized employee must place his or her personal lock on each energy-isolating device before beginning service work. Service work involving many workers and many energy-isolating devices can make traditional lockout complicated.

Before any work begins on machines or equipment that have been locked out or tagged out, an authorized employee must verify that the machine or equipment has been properly isolated and de-energized.

Energy Control Devices

Watch this informative video produced by Brady on the application of various lockout/tagout devices.


Before beginning this quiz, we highly recommend you review the module material. This quiz is designed to allow you to self-check your comprehension of the module content, but only focuses on key concepts and ideas.

Read each question carefully. Select the best answer, even if more than one answer seems possible. When done, click on the "Get Quiz Answers" button. If you do not answer all the questions, you will receive an error message.

Good luck!

1. To control hazardous energy, you have to prevent it from being transmitted from its _____ to the _____.

2. What is the first step in controlling energy on equipment that needs maintenance in your workplace?

3. During shutdown, what must be located to control the equipment or machine's energy source?

4. A lockout device is typically a _____.

5. After the energy-isolating device has been locked out or tagged out, only known hazardous stored or residual energy must be relieved, disconnected, restrained, and otherwise rendered safe.

Have a great day!

Important! You will receive an "error" message unless all questions are answered.