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March 28, 2002

The Importance of Lockout/Tagout

By Maureen Alvarez, CIH, CSP

Why is controlling hazardous energy sources important?  Employees servicing or maintaining machines or equipment may be exposed to serious physical harm or death if hazardous energy is not properly controlled. 

Craft workers, machine operators, and laborers are among the 3 million workers who service equipment and face the greatest risk.  Compliance with the lockout/tagout standard prevents an estimated 120 fatalities and 50,000 injuries each year.  Workers injured on the job from exposure to hazardous energy lose an average of 24 workdays for recuperation.

Energy Sources

Most people immediately think of electricity as a potentially hazardous energy source. There are other sources of energy, though, that can be just as hazardous.  These energy sources include thermal, chemical, pneumatic, hydraulic, mechanical, and gravity.  It is important to remember that all sources of energy that have the potential to unexpectedly start-up, energize, or release must be identified and locked, blocked, or released before servicing or maintenance is performed.

The OSHA standard for The Control of Hazardous Energy (Lockout/Tagout), Title 29 CFR, Part 1910.147, addresses the practices and procedures necessary to disable machinery or equipment, thereby preventing the release of hazardous energy while employees perform servicing and maintenance activities. 

This standard is designed to prevent the unexpected start-up, or energizing of machinery and equipment which could cause injury to employees.  It is also designed to prevent the release of stored energy which could cause injury to employees. 

In addition, 29 CFR 1910.333 sets forth requirements to protect employees working on electric circuits and equipment.  This section requires workers to use safe work practices, including lockout and tagging procedures.  These provisions apply when employees are exposed to electrical hazards while working on, near, or with conductors or systems that use electric energy.

Written Lockout/Tagout Program

The lockout/tagout standard establishes the employer's responsibility to protect employees from hazardous energy sources on machines and equipment during service and maintenance. 

The standard gives each employer the flexibility to develop an energy control program suited to the needs of the particular workplace and the types of machines and equipment being maintained or serviced.  This is generally done by affixing the appropriate lockout or tagout devices to energy-isolating devices and by de-energizing machines and equipment.  The standard outlines the steps required to do this.

In order to comply, a company must prepare a written Lockout/Tagout Program which includes the scope, purpose, authorization, rules, and techniques to be utilized in the control of hazardous energy. Training must also be provided to all employees who are affected by the Lockout/Tagout procedures.

All employees working in an area requiring lockout/tagout procedures must be trained. Training must include:

  1. The recognition of lockout/tagout devices and the importance of not disturbing or removing them unless authorized.
  2. The safe application, use, and removal of energy controls,
  3. The limitations of tags in a lockout/tagout procedure.

Training must occur whenever there is a change in job assignment, a change in machinery or equipment, an energy control procedure change, or a change in a process that presents a new hazard.  Retraining is to be conducted whenever the employer believes that employees' knowledge of energy control procedures is inadequate and as part of the annual inspection.


The basic equipment needed for a lockout/tagout procedure are locks and/or tags. Locks are to be utilized whenever possible. Both locks and tags must clearly indicate the identity of the employee who applied the device. This provides positive identification as to who is servicing the machinery and equipment. The identification will also indicate who may not have finished working in a multiple lockout/tagout situation.

An energy isolating device is simply a mechanical device that physically prevents the transmission or release of energy.  All machinery and equipment must be designed to accept a lockout device when major replacements, repairs, renovations, modifications of machinery or equipment are performed, or whenever new machinery is installed.

An audit should be conducted on all machines and equipment to identify all potentially dangerous energy sources and all energy isolating devices.  By doing this, employers will be able to establish all appropriate lockout/tagout procedures.

Outside Personnel

When outside personnel, such as contractors, are on site and engaged in activities that require compliance with the Lockout/Tagout Standard, the on-site employer and the outside employer must inform one another of their lockout/tagout procedures.  It is the responsibility of the on-site employer to ensure that his/her employees understand and comply with the methods of the other's lockout/tagout procedures.


What must employers do to protect employees?  Some of the most critical requirements from the lockout/tagout standards are as follows:

  • Develop, document, implement and enforce an energy control program.
  • Use lockout devices for equipment that can be locked out.
  • Ensure that new or overhauled equipment is capable of being locked out.
  • Develop, implement and enforce an effective tagout program if machines or equipment are not capable of being locked out.
  • Use only lockout/tagout devices authorized for the particular equipment or machinery and ensure that they are durable, standardized and substantial.
  • Ensure that lockout/tagout devices identify the individual users.
  • Establish a policy that permits only the employee who applied a lockout/tagout device to remove it.
  • Inspect energy control procedures at least annually.
  • Provide effective training for all employees as covered by the standard.

For additional information visit the OSHA web page at www.osha.gov.

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