Hazard Overview:  Every year, unexpected and uncontrolled releases of hazardous energy cause worker injuries and deaths during the installation, maintenance, service, or repair of machines, equipment, processes, or systems.

Hazardous energy is any type of energy that is powerful enough to cause injury to a worker and includes electricity, mechanical motion, pressurized air, and hot and cold temperatures.   Workers can be exposed to hazardous energy in several forms and combinations:

  1. Kinetic (mechanical) energy in the moving parts of mechanical systems
  2. Potential energy stored in pressure vessels, gas tanks, hydraulic or pneumatic systems, and springs (potential energy can be released as hazardous kinetic energy)
  3. Electrical energy from generated electrical power, static sources, or electrical storage devices (such as batteries or capacitors)
  4. Thermal energy (high or low temperature) resulting from mechanical work, radiation, chemical reaction, or electrical resistance


The following steps should be considered when developing a Lockout/Tagout program:

  1. Develop and implement a hazardous energy control program that requires workers to secure energy control devices with their own individually assigned locks and keys (only one key for each lock the worker controls). Each lock used to secure an energy control device should be clearly labeled with durable tags to identify the worker assigned to the lock and only the worker who installs the lock can remove it after all work is completed.  If work is not completed when the shift changes, workers arriving on the next shift should apply their own locks before the departing workers remove their locks.
  2. Identify and label all hazardous energy sources.
  3. De-energize, isolate, block, and/or dissipate all forms of hazardous energy before work begins.
  4. Verify by test and/or observation that all energy sources are de-energized before work begins.
  5. Inspect repair work before reactivating the equipment.
  6. Make sure that all workers are clear of danger points before re-energizing the system.
  7. Train ALL workers in the basic concepts of hazardous energy control.
  8. Include a hazardous energy control program with any confined-space entry program.
  9. Encourage manufacturers to design machines and systems that simplify hazardous energy control.

Lockout/Tagout Procedure

Procedures vary depending upon 1) whether the source of hazardous energy is electrical, hydraulic, pneumatic, mechanical, thermal or chemical, and 2) how many employees are affected.

Taking Equipment Out of Service

  1. First notify all personnel that specific equipment will be shut down.
  2. Shut down the equipment by normal operating procedures.
  3. Isolate all the equipment’s energy sources. If the equipment’s energy source is an engine that powers only that equipment, shut down the engine.
  4. Lockout/Tagout the energy-isolating devices.
  5. Release or restrain any stored energy by grounding, blocking, bleeding down, etc.
  6. Assure that no personnel are exposed, then test the equipment to assure that it will not operate.

Restoring Equipment to Service

  1. Check to assure that all employees have been safely positioned or removed from the area.
  2. Verify that equipment controls are in neutral.
  3. Remove lockout devices and tags and re-energize the equipment power source.
  4. Notify the affected employees that the equipment is ready for use.