OSHA Lockout/Tagout – Control of Hazardous Energy

Machines and equipment can contain hazardous energy even after they have been turned off. Unexpected startup, energization, or the release of stored energy during servicing or maintenance can cause electrocution, crushing injuries, amputations, burns, and other serious injuries.

OSHA’s Lockout/Tagout standard, 29 CFR 1910.147 – The Control of Hazardous Energy, establishes requirements for controlling hazardous energy during servicing and maintenance of machines and equipment.

Lockout/tagout is commonly abbreviated as LOTO.

What Is Lockout/Tagout?

Lockout/tagout is a system for preventing employees from being exposed to hazardous energy while servicing or maintaining machines and equipment.

Before covered servicing or maintenance begins, equipment must be shut down and hazardous energy sources controlled so the machine cannot unexpectedly start, become energized, or release stored energy.

Depending on the equipment, hazardous energy may include:

• Electrical energy.
• Mechanical energy.
• Hydraulic pressure.
• Pneumatic pressure.
• Chemical energy.
• Thermal energy.
• Gravity.
• Springs, flywheels, elevated components, or other stored energy.

Simply turning off a machine with its normal operating controls does not necessarily control these hazards.

OSHA Lockout/Tagout Requirements

OSHA requires employers covered by the standard to establish an energy control program consisting of energy control procedures, employee training, and periodic inspections.

The program must provide for the control of hazardous energy whenever employees perform servicing or maintenance where unexpected energization, startup, or release of stored energy could cause injury.

The specific procedures depend on the machinery, energy sources, servicing activities, and workplace conditions involved.

Lockout vs. Tagout

Lockout involves placing a lockout device on an energy-isolating device so the equipment cannot be operated until the device is removed.

Tagout involves placing a tagout device on an energy-isolating device to warn employees that the equipment must not be operated.

A tag is primarily a warning device. Unlike a lock, it does not provide the physical restraint of an energy-isolating device.

When an energy-isolating device is capable of being locked out, OSHA generally requires lockout unless the employer can demonstrate that the tagout program provides employee protection equivalent to that provided by a lockout program.

Energy Control Procedures

Employers must develop, document, and use procedures for controlling potentially hazardous energy when employees are engaged in covered servicing and maintenance.

Procedures should clearly address the steps necessary to:

• Prepare for shutdown.
• Shut down the machine or equipment.
• Isolate energy sources.
• Apply lockout or tagout devices.
• Control or dissipate stored and residual energy.
• Verify that energy isolation is effective.
• Perform the servicing or maintenance work.
• Remove lockout or tagout devices.
• Restore the machine or equipment to service.

Employees must understand and follow the energy control procedure applicable to the equipment being serviced.

Stored and Residual Energy

Disconnecting the primary power source may not eliminate all hazardous energy.

Stored or residual energy can remain in:

• Capacitors.
• Hydraulic and pneumatic systems.
• Pressurized lines and vessels.
• Springs.
• Flywheels.
• Elevated machine components.
• Heated equipment or materials.
• Mechanical systems capable of movement.

Stored energy must be relieved, disconnected, restrained, blocked, or otherwise rendered safe.

If stored energy can reaccumulate to a hazardous level, employees must continue verifying isolation until the servicing or maintenance is completed or the possibility of reaccumulation no longer exists.

Verification of Isolation

Before work begins, an authorized employee must verify that isolation and deenergization of the machine or equipment have been accomplished.

Verification is a critical step. Applying locks and tags does not by itself prove that all energy sources have been isolated.

The method of verification depends on the equipment and energy involved and may include attempting normal operating controls, testing electrical circuits with appropriate instruments, checking pressure gauges, or otherwise confirming a zero-energy or safe condition.

Authorized, Affected, and Other Employees

OSHA’s Lockout/Tagout standard distinguishes between different categories of employees.

Authorized employees perform lockout or tagout in order to service or maintain equipment.

Affected employees operate or use equipment being serviced under lockout/tagout or work in an area where such servicing is being performed.

Other employees may work in or pass through areas where energy control procedures are used.

The amount and type of training required depends on the employee’s role.

Lockout/Tagout Training

Authorized employees must receive training concerning the recognition of applicable hazardous energy sources, the type and magnitude of energy present, and the methods and means necessary for energy isolation and control.

Affected employees must be instructed in the purpose and use of the energy control procedure.

Other employees whose work may take them into an area where energy control procedures are used must be instructed about the procedure and the prohibition against restarting or reenergizing locked- or tagged-out equipment.

Retraining is required when specified changes or deficiencies create a need for additional instruction.

Periodic Inspections

OSHA requires employers to conduct a periodic inspection of each energy control procedure at least annually.

The inspection is intended to verify that the procedure and the requirements of the Lockout/Tagout standard are being followed and to identify and correct deviations or inadequacies.

The inspection must be performed by an authorized employee other than the employees using the energy control procedure being inspected.

Employers must certify that the required periodic inspections have been performed.

Group Lockout/Tagout

Servicing and maintenance sometimes involve crews, departments, contractors, or multiple employees working on the same equipment.

OSHA requires group lockout/tagout procedures to provide each authorized employee with a level of protection equivalent to that provided by an individual lockout or tagout device.

Each authorized employee generally applies a personal lockout or tagout device to the group lockout device, group lockbox, or comparable mechanism when beginning work and removes it when finished.

Shift and Personnel Changes

Energy control must remain effective when servicing extends across shifts or when employees are replaced during the work.

Employers must establish specific procedures for orderly transfer of lockout/tagout protection between employees so that continuity of protection is maintained.

No employee should be exposed to hazardous energy simply because a shift changes.

Outside Contractors

When outside servicing personnel are involved in activities covered by the Lockout/Tagout standard, the onsite employer and outside employer must inform each other of their respective lockout or tagout procedures.

The onsite employer must ensure its employees understand and comply with the restrictions and prohibitions of the outside employer’s energy control program.

When Lockout/Tagout Applies

OSHA’s standard generally applies to servicing and maintenance where unexpected energization or startup of machinery or equipment, or release of stored energy, could injure employees.

Certain activities and situations are excluded or addressed differently under the standard. For example, some minor servicing activities performed during normal production operations may qualify for a limited exception when all of OSHA’s conditions are satisfied.

Employers should not assume an activity is exempt merely because the work is brief or routinely performed.

Preventing Hazardous Energy Injuries

Effective lockout/tagout requires more than placing a padlock on a disconnect.

Employers must identify all energy sources, establish appropriate energy control procedures, train employees according to their responsibilities, control stored energy, verify isolation before work begins, coordinate group and contractor activities, and inspect energy control procedures at least annually.

For additional regulatory information, see OSHA 29 CFR 1910.147 – The Control of Hazardous Energy (Lockout/Tagout).

For company-specific responsibilities, procedures, equipment requirements, inspections, training, and documentation, refer to the company’s Lockout/Tagout Program.