Control of Hazardous Energy (Lockout/Tagout) (8/11/11)



[Editor's Note:  This is the second in a series of "Safety First!" columns that will appear periodically to reiterate the importance of observing practical and effective safety practices in the workplace to protect employee safety and health.]

Locking out and tagging electrically charged equipment is an important component of a facility safety program to protect employees.

The Occupational Safety and Health Administration (OSHA) regulates lockout/tagout under its "control of hazardous energy standard" [29 CFR ยง1910.147]. This standard mandates training, audits and recordkeeping to protect workers from being unintentionally injured by the unexpected energization, start-up, or release of electrical, mechanical, hydraulic, pneumatic, chemical, thermal or any other type of energy.  In CPL 02-00-147, OSHA established policies and provided clarifications as to how it will enforce this standard.

What is Lockout/Tagout?  Lockout/tagout is designed to prevent the accidental start-up of machines or other equipment during maintenance or servicing to protect the safety and health of employees, and safeguard equipment from damage.

Lock-out (deenergizing) is the process of blocking the flow of energy from a power source to a piece of equipment, and keeping it blocked out.
  • Lock-out is accomplished by installing a lock-out device at the power source so that equipment powered by that source cannot be operated.  A lock-out device is a lock, block, or chain that keeps a valve or lever in the off position.

  • Locks are provided by the employer and can be used only for lock-out purposes. They never should be used to lock tool boxes, storage sheds or other devices.
In general, the deenergizing procedure consists of:
  • Informing all affected employees of the impending shut down.

  • Shutting down the machine by following the normal method for shutdown.

  • Turning off the energy at the main power source.

  • Locking out all energy sources involved, using unique locks not used for other purposes.

  • Releasing and/or relieving all sources of stored energy.

  • Turning the machine back on to confirm that the power source has been deactivated.

  • Attempting to restart the machine to guarantee that the power is shut off, then returning the switch to the off position.
Following the lock-out procedure, the employee will "tag-out" the equipment by placing a tag on the power source.  The tag acts as a warning signal not to restore energy.  But it is not a physical restraint. Tags are to state clearly, "Do not operate" or similar language, and  are to be applied by hand using a non-reusable nylon cable tie (or an equivalent attachment device).  Both locks and tags are to be strong enough to prevent unauthorized removal and to withstand various environmental conditions.

Additional employer requirements:
  • Develop written machine-specific procedures for locking out each piece of equipment or each generic grouping of equipment (such as augers)

  • Periodically "field test" all authorized employees on locking out each energy source they are authorized to lock out.
Additional information and resources on lock-out/tag-out are available at: