SUBJECT: Control of Hazardous Energy (Lockout/Tagout)
ORIGINAL: December 21, 1994
LAST UPDATED: October 13, 2009

Table of Contents


Occupational Safety and Health Administration Standard 29 CFR 1910.147; Control of Hazardous Energy.


This standard establishes the minimum requirements for the lockout of hazardous energy whenever maintenance or servicing is performed on machines or equipment. It shall be used to ensure that the machine or equipment is de-energized , isolated from all potentially hazardous energy sources and locked out before employees perform any servicing or maintenance where the unexpected energization or start-up of the machine or equipment or release of stored energy could cause injury.


A safe and healthful campus environment shall be provided for all UW-L employees, students, guests and residents of the community. When engineering or administrative controls will not provide an acceptable level of protection, personal protective equipment will be provided to achieve safe working conditions. This standard applies to the control of hazardous energy during servicing and/or maintenance of machines and equipment if:

  1. An employee is required to remove or bypass a guard or other safety device; or
  2. An employee is required to place any part of their body into an area on a machine or piece of equipment where work is being performed at or upon the point of operation, or when an associated danger zone exists during a machine operating cycle.

This standard does not apply to work on cord-and-plug connected electrical equipment when the employee performing the service or maintenance controls energization by unplugging the equipment from the energy source. The standard also does not apply to hot tap operations involving transmission systems from substances such as gas, steam, water, or petroleum, when they are performed on pressurized pipelines. However, it must be demonstrated that the continuity of service is essential, shut off of the system is impractical, and special equipment is used which provides effective protection. Approval must be granted by the Director or Assistant Director of Facilities Management prior to any hot tap operations.


Affected person: An individual who operates or works near equipment which is being serviced or maintained while locked or tagged out. The affected person does not perform servicing or maintenance on machines or equipment.

Authorized employee: An employee who locks out or tags out machines or equipment in order to perform servicing or maintenance on that machine or equipment.

Energized: Connected to an energy source or containing residual or stored energy.

Energy isolating device: A mechanical device that physically prevents the transmission or release of energy. These include, but are not limited to, manually operated disconnect switches, line valves, blocks and slide gates. Push buttons, selector switches and other control circuit type devices are not energy isolating devices.

Energy source: Any source of electrical, mechanical, hydraulic, pneumatic, chemical, thermal, or other energy.

Hot tap: A procedure used in the repair, maintenance and services activities which involves welding on a piece of equipment (i.e., pipelines, vessels and tanks) under pressure, in order to install connections.

Lockout: The placement of a lockout device on an energy isolating device, in accordance with an established procedure, ensuring that the energy isolating device and the equipment being controlled cannot be operated until the lockout device is removed.

Lockout device: Any device that uses positive means such as a lock, either key or combination type, to hold an energy isolating device in a safe position, thereby preventing the energizing of machinery or equipment. When properly installed, a blank flange or bolted slip blind are considered equivalent to lockout devices.

Servicing and/or maintenance: Workplace activities such as constructing, installing, setting up, adjusting, inspecting, modifying, and maintaining and/or servicing machines or equipment. These activities include lubrication, cleaning or unjamming of machines or equipment and making adjustments or tools changes, where the employee may be exposed to the unexpected energization or start-up of the equipment or release of hazardous energy.

Tagout: The placement of a tagout device on an energy isolating device, in accordance with an established procedure, to indicate that the energy isolating device and the equipment being controlled may not be operated until the tagout device is removed.

Tagout device: A prominent warning device, such as a tag and a means of attachment, which can be securely fastened to an energy isolating device in accordance with an established procedure, to indicate that the energy isolating device and the equipment being controlled may not be operated until the tagout device is removed.


Authorized employees shall use written energy control procedures when engaged in activities requiring compliance with this standard. The sequence of implementing energy control procedures is outlined in subsection V.A.. However, in some cases specific energy control procedures are required for machines and equipment.

A machine and/or equipment specific energy control procedure does not have to be developed when all of the following factors exist.

  1. There is no potential for stored or residual energy or re-accumulation of stored energy after shutdown;
  2. A single energy source can be readily identified and isolated;
  3. Isolation and locking out of the energy source prevents energizing and activation during servicing and/or maintenance;
  4. A single lockout device will achieve a locked-out condition;
  5. The lockout device is under the exclusive control of the authorized employee;
  6. Servicing and/or maintenance does not create hazards for other employees; and
  7. Use of this exemption has resulted in no accidents involving unexpected activation or re-energization during servicing and/or maintenance.

In cases where written procedures need to be developed for particular machines or equipment the organization responsible for maintenance and/or servicing the machine or equipment shall develop written procedures using the form included in Appendix A. The machine or equipment specific procedures shall be maintained in a location that is readily accessible to the authorized employee.

A. Sequence of Lockout/Tagout

  1. The authorized employee shall identify the type and magnitude of the energy source that the know machine or equipment utilizes, understand the hazards of each energy source and shall know the methods to control the energy source.
  2. The authorized employee shall notify each affected person that servicing or maintenance is required on a machine or equipment and that the machine or equipment must be shut down and locked out to perform the servicing or maintenance.
  3. Shut down the machine using normal stopping procedures.
  4. Isolate all energy sources.
  5. Attach lockout devices to all energy isolating devices operated in step 4. In addition, attach a tag bearing the identity of the lockout device and lock owner.

    If a tagout device is used in lieu of a lock when the energy isolating device is incapable of lockout to at least one additional safety measure shall be used that provides a level of safety equivalent to that of use of a lock. Such safety measures include, but are not limited to, opening an additional disconnecting device, removal of an isolating circuit element, blocking of a controlling switch or the removal of a valve handle. All personnel must be able to understand the hazard warning written on the tags, such as: DO NOT START, DO NOT OPEN, DO NOT CLOSE, DO NOT ENERGIZE, or DO NOT OPERATE.

  6. Stored or residual energy such as that in capacitors, springs, rotating flywheels, hydraulic systems, steam or water pressure lines, compressed air, gas or chemical lines and any other secondary or energies must be dissipated or restrained by methods such as grounding, repositioning, or blocking.
  7. The authorized employee shall verify that the machine is locked out by testing the machine operating controls. All controls shall be returned to the "Neutral" or "Off" position after testing.
  8. The machine is now properly locked out and service or repairs can safely begin.

B. Temporary Release of Lockout/Tagout

When it is necessary to temporarily remove lockout/tagout devices in order to test or position machines or equipment all authorized employee's shall:

  1. Visually inspect the machine to be sure it is operationally intact, tools have been removed and that items that may pose a hazard upon activation are controlled.
  2. Visually inspect the work area to ensure that all employees have been safely positioned or removed from any hazardous area.
  3. Verify that the controls are in neutral.
  4. Remove the lockout and/or tagout devices and proceed with testing or positioning.
  5. De-energize all systems and reapply lockout/tagout as described in subsection V.A..

C. Restoring Equipment to Service

When servicing or maintenance is completed and the machine or equipment is ready to return to normal operating condition, the following steps shall be taken by the authorized employee.

  1. Visually inspect the machine to be sure it is operationally intact, tools have been removed and guards have been replaced.
  2. Visually inspect the work area to ensure that all employees have been safely positioned or removed from any hazardous area.
  3. Verify that the controls are in neutral.
  4. Remove the lockout and/or tagout devices and reenergize the machine or equipment.
  5. Notify affected personnel that the servicing or maintenance is completed and the machine or equipment is ready to use.


If more than one individual is required to lockout equipment each authorized employee shall place their personal lockout device on the energy isolating device(s). When an energy isolating device cannot accept multiple locks, a multiple lockout or tagout device (hasp) shall be used.


An authorized employee may transfer lockout/tagout protection to a second authorized employee. The second authorized employee shall place their lockout and/or tagout device prior to or at the time the original authorized employee removes their lockout and/or tagout devices.

When shift changes or other circumstances may prevent the two authorized employee's from being on site at the same time a shift lock shall be used. An authorized employee's supervisor should install the shift lock. No person shall work under the protection of a shift lock. The supervisor attaching the shift lock shall transfer lockout/tagout protection prior to additional work on the machine or equipment.


If a lock has been left in place by an authorized employee who has departed the campus it can be removed only if deemed necessary by the authorized employee's supervisor or other supervisor responsible for the equipment, machine or area. In such cases the lock shall be removed only by adherence to the following procedures.

  1. A thorough inspection of the equipment is to be made by the supervisor.
  2. The supervisor must confirm that the authorized employee who applied the lock-out device is not on campus.
  3. The supervisor can remove the lock providing they have determined starting up the equipment will not endanger other personnel.
  4. Each time it is necessary to remove/cut a safety lock a written report shall be prepared by the supervisor authorizing lock removal. The report should include the type of equipment, justification for lock removal and actions taken to notify the individuals lock being removed.
  5. The supervisor shall make a reasonable effort to contact the employee who originally applied the lock to inform them that the device has been removed. This contact is necessary so that the affected employee would be informed that this has occurred prior to resuming work.


Specifications for lockout and tagout equipment are included in the following list.

  1. Lockout and tagout devices shall be standardized for the campus.
  2. Tagout devices shall indicate the identity of the employee applying the device(s).
  3. All locks will be marked with the identification of the user and shall have color-coded bumpers to designate the work groups. Color-codes are assigned as follows:
    • Yellow: Physical Plant Carpenter Shop
    • Red: Physical Plant - Mechanics, Plumbers, Electricians and Heating Plant
    • Blue: General campus
  4. The standard lock will be Masterlock model 21 or an equivalent.
  5. Locks for each employee will be keyed differently and have no master key.
  6. Lockout devices must be capable of locking the device in an off position. While in the locked position the lockout device shall not be easy to remove. Lockout devices can range from purchased devices to chains.

All locks shall be acquired through the Campus Locksmith in the Physical Plant.

Lockout and tagout devices can be purchased through Campus Stores or through other approved methods. Since there are a wide variety of lockout devices, Campus Stores will special order or maintain a limited selection of lockout and tagout devices. Specialty lockout devices can be purchased through a variety of safety supply vendors. Personnel can contact the Environmental Health and Safety Office if assistance is required in identifying equipment or vendors.


Each authorized employee shall receive training in the 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 shall be instructed in the purpose and use of the energy control procedure.

All other employees whose work operations are or may be in an area where energy control procedures may be utilized, shall be instructed about the procedure, and about the prohibition relating to attempts to restart or reenergize machines or equipment which are locked out or tagged out.

Employees must also be trained about the following limitations for use of tagout devices.

  1. Tags are warning devices and do not provide physical protection.
  2. Tags may evoke a false sense of security.
  3. Tags must be legible and understandable.
  4. Tags and their means of attachment must withstand the environment in which they are used.
  5. A tag may only be removed with approval of the authorized employee.
  6. Tags must be securely attached to prevent accidental detachment.

Authorized employees shall be retrained and affected employees reinstructed when their job assignment changes, when a change in machines or equipment presents a new hazard, when periodic inspection indicates employees are not properly adhering to the energy control procedure, or when energy control procedures change.


A periodic inspection of each procedure, where usage is at least once a year, must be performed at least annually to assure that the energy control procedures continue to be implemented properly and that the employees are familiar with their responsibilities under those procedures.

The individual(s) who conduct these inspections must be proficient enough with the equipment and/or process to certify correctness. The inspector shall complete their audit with the form included in Appendix B. The inspection shall not be performed by the authorized employee using the energy control procedure.


Whenever contractors come onto campus to perform installation, service and/or maintenance work the contractor and UW-L shall inform each other of their respective lockout or tagout procedures. The individual responsible for project management or interface with contractors must take reasonable actions to inform campus employees of the contractors energy control procedures that vary from those specified in this standard.


The Control of Hazardous Energy (Lockout/Tagout) standard is effective immediately. All University of Wisconsin - La Crosse employees shall fulfill their responsibilities as designated within this written standard.