Control Of Hazardous Energy (Lockout/Tagout)

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 equipment

Scope and Application

The 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 situations:

Servicing and/or Maintenance Operations

If a 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:

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.

Employees 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 effective protection.

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.

The energy 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 elements:

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.

In addition, 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.

Energy-Isolating Devices

The 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 attached.

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 lockable.

Requirements for Lockout/Tagout Devices

When 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 following requirements:

Application of Lockout/Tagout Devices

The established procedure of applying energy controls includes the specific elements and actions that must be implemented in sequence.  These are briefly identified as follows:

  1. Prepare for shutdown.
  2. Shut down the machine or equipment.
  3. Disconnect the energy-isolating device.
  4. Apply the lockout or tagout device.
  5. Render safe all stored or residual energy
  6. Verify the isolation and deenergization of the machine or equipment.

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:

  1. Inspect the work area to ensure that non-essential items have been removed and that machine or equipment components are intact and capable of operating properly.
  2. Check the area around the machine or equipment to ensure that all employees have been safely positioned or removed.
  3. Make sure that locks or tags are removed only by those employees who attached them.
  4. Notify affected employees after removing locks or tags and before starting equipment or machines.

Employee Training

The 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 following areas:

  1. recognition of applicable hazardous energy sources,
  2. details about the type and magnitude of the hazardous energy sources present in the workplace, and

  3. 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.