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Learning Objectives

  • Identify the purpose of a lockout/tagout system.
  • Identify typical locks and tags and their use.
  • Identify limitations of tags.

Available in English

15 minutes

Workers injured on the job from exposure to hazardous energy lose an average of 24 workdays for recuperation.

Environmental Health & Safety News

To protect workers from the serious hazards posed by the unexpected start-up or operation of equipment during repair or maintenance, the Occupational Safety & Health Administration (OSHA) has established a Control of Hazardous Energy standard. It is commonly referred to as the lockout/tagout (LOTO), or energy isolation standard. This standard requires the application of markings and barriers that prevent unauthorized persons from energizing and operating equipment. 

Energy in any form becomes hazardous when it builds to a certain level, or is released inadvertently or unexpectedly. Lockout/tagout refers to specific practices and procedures that safeguard employees from the unexpected startup of machinery and equipment, or the release of hazardous energy, during service or maintenance activities.

The lockout/tagout standard requires that only a qualified, authorized individual is allowed to use an energy-isolating device to turn off and disconnect machinery or equipment from energy sources before performing service or maintenance. This designated individual may also apply a lockout device, such as a hasp or chain, to prevent the machinery from being turned on again. The standard also requires that the authorized employee(s) tag the energy-isolating device or devices to warn others not to re-energize the equipment and to take steps to verify that the energy has been isolated effectively.

The lockout/tagout standard requires employers to establish an energy-control program that ensures only trained and authorized employees isolate machines from energy sources and render machines inoperative before any other employee may service or maintain them.

When it is not possible to lock a de-energized energy source, only a tag may be used. Tags without locks should be treated as if they were locks. The identity of the person who placed the tag must be described on the tag. This usually includes the person’s name and contact information, such as a phone number. 

Let’s run through three basic rules related to the lockout/tagout standard…

Employees should never attempt to remove a lock or tag, or operate a piece of equipment that is locked or tagged.

Locks used for isolating energy sources are required to be dedicated, marked, and not used for any other purpose.

Tags associated with lockout/tagout activities are red, to communicate ‘danger’. They may have different warnings printed on them, such as ‘Do Not Operate’, ‘Do Not Start’, ‘Do Not Open’, ‘Do Not Close’, or ‘Do Not Energize’. Both locks and tags must be constructed to withstand the environment in which they are used.

Purpose of Locks and Tags

  • To ensure that a machine has been  isolated or disconnected from its power source
  • To prevent unwanted startup when repairing equipment
  • Warning tags may be used, but they must provide the same level of safety as a lock
  • Tags provide  temporary warnings until equipment can be locked-out
  • Locks and tags can also establish safe boundaries

Locks and Tags

  • Do not remove without authorization of the person or organization responsible for it
  • Never bypass or ignore
  • Use locks whenever physically possible
  • May use tags instead of locks as long as an equivalent level of safety is afforded by some other means

Tags must be:

  • Legible and understandable
  • Made of materials which will withstand environmental conditions encountered
  • Securely attached and bear the name of the person placing it

Danger tags indicate:

  • Immediate danger
  • Special precautions are necessary

Caution tags indicate:

  • Possible hazard
  • Need for proper precaution

Follow lockout/tagout procedures and do not operate locked or tagged equipment or systems.

Locks physically prevent the operation of valves, electrical breakers, and other energy controlling devices. Locks are the preferred method of isolating systems and equipment. Some companies use locks in conjunction with tags.

Tags show a ‘signal’ word, such as DANGER or CAUTION. They are usually white and display the word “DANGER” in red letters on a black background and include instructions such as “Do Not Operate”. They may be attached at the location of the start or turn-on switch. Tags are usually placed on isolation boundaries to warn personnel that the equipment has been placed in a specific position for safety reasons. Tags may only be removed by the person or organization who placed the tag.

Only those employees who have been properly trained in lockout/tagout procedures can be designated as an “Authorized Employee” by the employer. 

Multiple Locks

  • Each Authorized Employee must apply locks to the energy isolation points
  • Must be keyed differently so no more than one person’s key will open a lock
  • If a combination lock is used, only the person placing the lock must know the combination to open it
  • Typical lockout devices do not accept more than one lock
  • One way to apply multiple locks is to use a special device called a scissor hasp

Companies are required to ensure all employees understand the purpose and function of the energy control program. OSHA categorizes employees into three groups: Authorized Employees, Affected Employees, and others. Authorized Employees are the only people allowed to apply locks or tags and perform work on isolated equipment. Affected Employees are people who work around isolated equipment, but not on it. OSHA requires that each Authorized Employee receive additional training in recognition of applicable hazardous energy sources, the type and magnitude of the energy available in the workplace, and the methods and means necessary for energy isolation and control.

Each affected employee must be trained in the purpose and use of the company's hazardous energy control procedure. All other employees whose work operations are or may be in an area where energy control procedures may be used must be trained not to attempt to operate equipment that is locked or tagged. In addition, they must receive training on the company's hazardous energy control procedure.

Limitations of Using Tags Only

  • Tags can only convey strong warnings
  • Tags do not provide the physical restraint on devices that can be provided by a lock
  • Tags may evoke a false sense of security
  • Don't remove, ignore, or bypass a tag
Course Outline
  • Introduction
  • Why You Should Use Locks and Tags
  • Locks and Tags
  • Training and Procedures
  • 29 CFR 1910.331
  • 29 CFR 1910.332
  • 29 CFR 1910.147
  • 29 CFR 1910.147 Appendix A