On September 1, 1989, OSHA issued a
final rule on the Control of Hazardous Energy (Lockout/Tagout) of Title 29 of
the Code of Federal Regulations (29 CFR) Part 1910.147. This standard, which went into effect on January 2, 1990,
helps safeguard employees from the unexpected startup of machines or equipment
or release of hazardous energy while they are performing servicing or
maintenance. The standard
identifies the practices and procedures necessary to shut down and lock out or
tag out machines and equipment, requires that employees receive training in
their role in the lockout/tagout program, and mandates that periodic inspections
be conducted to maintain or enhance the energy control program.
This rule requires that, in general, before service or maintenance is
performed on machines or equipment, the machines or equipment must be turned off
and disconnected from the energy source, and the energy-isolating device must be
either locked or tagged out. OSHA
has determined that lockout is a more reliable means of deenergizing equipment
than tagout and that it should always be the preferred method used by employees.
OSHA believes that, except for limited situations, the use of lockout
devices will provide a more secure and effective means of protecting employees
from the unexpected release of hazardous energy or startup of machines and
Scope and Application
lockout/tagout standard applies to general industry employment and covers the
servicing and maintenance of machines and equipment in which the unexpected
startup or the release of stored energy could cause injury to employees.
The standard applies to any source of mechanical, hydraulic, pneumatic,
chemical, thermal, or other energy, but does not cover electrical hazards.
Subpart S of 29 CFR Part 1910 covers electrical hazards, and 29 CFR Part
1910.333 contains specific lockout/tagout provisions for electrical hazards. The standard does not apply in the following
While servicing or maintaining cord and plug connected electrical equipment, provided that the equipment is unplugged from the energy source and the plug remains under the exclusive control of the employee performing the servicing.
During hot tap operations that involve
transmission and distribution systems for gas, steam, water, or petroleum
products when they are performed on pressurized pipelines.
This applies when continuity of service is essential, shutdown of the
system is impractical, and employees are provided with alternative
protection that is equally effective.
Servicing and/or Maintenance Operations
servicing activity such as lubricating, cleaning, or unjamming the production
equipment takes place during production, the employee performing the
servicing may be subjected to hazards that are not encountered as part of the
production operation itself. Workers
engaged in these operations are covered by lockout/tagout when any of the
following conditions occur:
The employee must either remove or bypass machine guards or other safety devices, resulting in exposure to hazards at the point of operation.
The employee is required to place any
part of his/her body in contact with the point of operation of the
operational machine or piece of equipment.
The employee is required to place any
part of his/her body into a danger zone associated with a machine operating
In the above situations, the equipment must be deenergized, and locks or tags must be applied to the energy isolation devices. In addition, when other servicing tasks occur such as setting up equipment or making significant adjustments to machines, employees performing such tasks are required to lock out or tag out if they can be injured by unexpected energization or startup of the equipment. OSHA also recognizes that some servicing operations must be performed with the power on. Making many types of fine adjustments, such as centering the belt on conveyors, is one example. Certain aspects of troubleshooting, such as identifying the source of the problem as well as checking to ensure that it has been corrected, is another. OSHA requires the employer to provide effective protection when employees perform such operations.
performing minor tool changes and adjustments and/or other minor servicing
activities that are routine, repetitive, and integral to the use of the
production equipment and that occur during normal production operations are not
covered by the lockout/tagout standard.
The work must be performed using alternative measures that provide
Provisions of the Standard
The standard requires employers to establish procedures for isolating machines or equipment from their source of energy and affixing appropriate locks or tags to energy isolating devices to prevent any unexpected energization, startup, or release of stored energy that could injure workers. When tags are used on energy isolating devices capable of being locked out, the employer must provide additional means to assure a level of protection equivalent to that of locks. The standard also requires the training of employees and periodic inspections of the procedures to maintain or improve their effectiveness.
The lockout/tagout rule requires that the employer establish an energy control program that includes (1) documented energy control procedures, (2) an employee training program, and (3) periodic inspections of the use of the procedures. The purpose of the energy control program is to ensure that the equipment is isolated from its energy source and rendered inoperative prior to servicing or maintenance whenever the possibility of unexpected machine or equipment startup exists. Employers have the flexibility to develop programs and procedures that meet the needs of their particular workplace and the particular types of machines and equipment being maintained or serviced.
control procedures must outline the scope, purpose, authorization, rules, and
techniques that will be used to control hazardous energy sources as well as the
means that will be used to enforce compliance.
At a minimum they should include, but not be limited, to the following
A statement on how the procedures will
The procedural steps needed to shut
down, isolate, block, and secure machines or equipment.
The steps designating the safe
placement, removal, and transfer of lockout/tagout devices and who has the
responsibility for them.
The specific requirements for testing
machines or equipment to determine and verify the effectiveness of locks, tags,
and other energy control measures.
The employer or an authorized employee must notify affected employees before lockout or tagout devices are applied and after they are removed from the machine or equipment.
The procedures must include the following:
steps: (1) preparing for shutdown, (2) shutting down the machine or equipment, (3) isolating the machine or equipment from the energy source, (4) applying the lockout or tagout devices to the energy isolating devices, (5) safely releasing all potentially hazardous stored or residual energy, and (6) verifying the isolation of the machine or equipment prior to the start of servicing or maintenance work.
before lockout or tagout devices are removed and energy is restored to the
machines or equipment, certain steps must be taken to reenergize equipment after
servicing is completed. This
includes (1) ensuring that machines or equipment components are operationally
intact, (2) ensuring that all employees are safely positioned or removed from
equipment, and (3) ensuring that lockout or tagout devices are removed from each
energy-isolating device by the employee who applied the device.
employer’s primary tool for providing protection under the standard is the
energy-isolating device, which is the mechanism that prevents the transmission
or release of energy and to which locks or tags are attached.
There are two types of energy isolating devices: those capable of being
locked and those that are not. If
the energy-isolating device is lockable, the employer must use locks unless he
or she can demonstrate that the use of tags would provide protection at least as
effective as locks and would assure “full employee protection.”
Full employee protection includes complying with all tagout related
provisions plus implementing additional safety measures that can provide the
level of safety equivalent to that obtained by using lockout.
This might include removing and isolating a circuit element, blocking a
controlling switch, opening an extra disconnecting device, or removing a valve
handle to reduce the potential for any inadvertent energization while tags are
Although OSHA acknowledges the existence of energy-isolating devices that
cannot be locked out, the standard clearly states that whenever major
replacement, repair, renovation, or modification of machines or equipment is
performed, the employer must ensure that the energy-isolating devices for such
machines or equipment are lockable. All newly purchased equipment must be
Requirements for Lockout/Tagout Devices
attached to an energy-isolating device, both lockout and tagout devices used in
accordance with the requirements of the standard help protect employees from
hazardous energy. A lockout device
provides protection by preventing the machine or equipment from becoming
energized. A tagout device does so
by identifying the energy-isolating device as a source of potential danger. It
indicates that the energy-isolating device and the equipment being controlled
may not be operated while the tagout device is in place.
Whichever devices are used, they must be singularly identified, must be
the only devices used for controlling hazardous energy, and must meet the
Lockout and tagout devices must withstand the environment to which they are
exposed for the maximum duration of the expected exposure.
Tagout devices must be constructed and printed so that they do not
deteriorate or become illegible, especially when used in corrosive or wet
Both lockout and tagout devices must be standardized according to color, shape,
or size. Tagout devices must also
be standardized according to print and format.
Lockout and tagout devices must be substantial enough to minimize early or
accidental removal. Locks must be
substantial enough to prevent removal except by excessive force of special tools
such as bolt cutters or other metal cutting tools.
Tag means of attachment must be nonreusable, attachable by hand,
self-locking, and nonreleasable, with a minimum unlocking strength of no less
than 50 pounds.
Locks and tags must clearly identify the employee who applies them.
Tags also must warn against hazardous conditions if the machine or
equipment is energized and must include a legend such as the following: DO NOT
START, DO NOT OPEN, DO NOT CLOSE, DO NOT ENERGIZE, DO NOT OPERATE.
Application of Lockout/Tagout Devices
established procedure of applying energy controls includes the specific elements
and actions that must be implemented in sequence.
These are briefly identified as follows:
Removal of Locks and Tags
Before lockout or tagout devices are removed and energy is restored to the machine or equipment, the authorized employee(s) must take the following actions or observe the following procedures:
employer must provide effective initial training and retraining as necessary and
must certify that such training has been given to all employees covered by the
standard. The certification must
contain each employee’s name and dates of training. For the purposes of the
standard, there are three types of employees—authorized, affected,
and other. The amount and
kind of training that each employee receives is based upon (1) the relationship
of that employee’s job to the machine or equipment being locked or tagged out
and (2) the degree of knowledge relevant to hazardous energy that he or she must
possess. For example, the
employer’s training program for authorized employees (those who are
charged with the responsibility for implementing the energy control procedures
and performing the servicing or maintenance) must cover, at a minimum, the
details about the type and magnitude of
the hazardous energy sources present in the workplace, and
the methods and means necessary to
isolate and control those energy sources.
By contrast, affected employees (usually the machine operators or users) and all other employees need only be able to (1) recognize when the control procedure is being used and (2) understand the purpose of the procedure and the importance of not attempting to start up or use the equipment that has been locked or tagged out. Because an “affected” or “other” employee is not performing the servicing or maintenance, that employee’s responsibilities under the energy control program are simple. Whenever there is a lockout or tagout device in place on an energy-isolating device, the affected or other employee must leave it alone and not attempt to energize or operate the equipment. Every employee training program must ensure that all employees understand the purpose, function, and restrictions of the energy control program and that authorized employees possess the knowledge and skills necessary for the safe application, use, and removal of energy controls.
Training programs for authorized employees to comply with this standard, which is performance oriented, should deal with the equipment, type(s) of energy, and hazard(s) specific to the workplace being covered. Retraining must be provided, as required, whenever there is a change in job assignments, a change in machines, equipment, or processes that present a new hazard or a change in energy control procedures. Additional retraining must be conducted whenever a periodic inspection reveals, or whenever the employer has reason to believe, that there are deviations from or inadequacies in the employee’s knowledge or use of the energy control procedures.