Lockout Tagout

LOTO devices reduce the risk of an unexpected equipment start-up by ensuring that an unauthorized worker cannot energize that equipment.


Lockout Tagout (LOTO) is a work practice that can reduce serious injury from electrocutions by ensuring equipment is properly de energized prior to maintenance construction or other such non-routine operations.  LOTO utilizes a system of locks or tags to ensure equipment or machinery remains de energized once de energized.  When installing, servicing or maintenance activities occur, an employee will cut power to the machinery and place a lock over the power source to ensure no other employee energizes the equipment while work is being performed. 

A lockout/tagout procedure is a best practice method that is put in place to aid in the prevention of the unexpected start-up, or energizing, of equipment or machinery while workers are engaging in non-routine production operations. This includes maintenance or servicing, or other operations that require a worker to extend a body part, their entire body, or otherwise come in close contact with, a machine while guards or other safety measures are not in place. While these actions may be needed for repairs or other such work, workers should never engage in these actions unless proper lockout/tagout procedures have been followed to help ensure their safety.

(Photo courtesy of ELCOSH)

LOTO for Electrical Systems

While performing non-routine production operations, equipment could be unintentionally started-up by an unauthorized employee who is unaware of the presence of a co-worker. A worker, who is either working on the equipment or in the vicinity of the equipment, could also accidently bump or fall onto a lever or switch, starting the equipment which could harm a worker. These or other similar actions can cause death or serious injury to a worker.  Electrocution or dismemberment may result without proper lockout/tagout procedures; however, with a proper system in place the likelihood of these incidents can be reduced.

Electrical system lockout devices include padlocks, electrical lockouts such as circuit breaker lockouts or push button switch covers, group lockouts, and cable lockouts.  Each of these different lockout systems is available in a variety of shapes and sizes, depending on the manufacturer, so the needs of most situations can be provided for.  Padlocks can be designed to be made of composite material, aluminum, or steel.  Each padlock provides a unique protection and can provide specialized assistance depending on the situation at hand.    

The padlocks that a company uses for lockout/tagout procedures should be different than the padlocks that are used in other parts of the facility for general uses.  The padlocks can be different in color, with a special color for lockout/tagout purposes, or the locks can be a different shape or a completely different type of padlock equipped with a designated label.  It is important that employees of a facility can easily distinguish between these locks so they are immediately aware of a lockout/tagout situation at their immediate approach.  Each employee at a facility should have their own lock with a unique key code, combination, etc.  This is an important requirement of every lockout/tagout program because employers need to ensure that the only employee who can remove a lock is the employee who placed the lock on a particular piece of equipment. 

Many companies have electronic programs in place to help employers ensure that their employees each have a unique key or combination.  For example, the company Master Lock® has a program that allows each employee key to be recorded and ensure no duplicates are offered.  It is voluntary for companies to participate in this program.  The only action employers must engage in is to enter their “key codes” into the database and save their registration number.  When additional locks are needed, the employer can simply give Master Lock® their registration number and they will verify that no duplicate codes are assigned to the new locks.

(Photo courtesy of ELCOSH)

Circuit breaker lockout devices are available in a variety of different sizes to compensate for the different sizes of breaker toggles.  Companies will generally offer a variety of circuit breaker lockout devices which range from universal devices to size-specific devices.  Additional types of electrical system lockout devices are push button and rotary switch covers and installation bases.  These types of devices are also available in a variety of sizes from most companies.  They work by restricting access to a button, control or switch because they will physically cover the area which prohibits an employee from accessing the button or switch.  One compensating feature of these devices is the clear cover or base that they are commonly equipped with.  This will allow an employee to clearly see the area that is being locked out, which adds to further clarification and understanding of the situation at hand. 

Group lockout devices are also common when non-routine production work must be completed.  These devices act by surrounding the power source once it has been de-energized and providing spaces for multiple employees to place their unique and individual locks.  Therefore, the equipment or machinery can not be re-energized until every individual who placed a lock on the device has removed their lock.  Each individual working on the equipment or machinery must place their own lock on the device to ensure adequate safety.  These devices are also available from a wide range of companies, which also offer different shapes and sizes to accommodate unique situations.  

In a situation where multiple circuit breaker panels or side-by-side gate valves need to be locked out, cable lockout devices can be used.  The cable will need to be fed through the spaces that are to be locked out and then back through the lockout device.  This will create a loop shape and will lockout the circuit breaker panel or gate valves.  These cables are made of tough and durable materials that are also able to tolerate many chemicals, making them suitable for the workplace. 

LOTO for Valves and Pipings

A need for lockout/tagout procedures can arise in many areas of the workplace, including tight spaces and insulated pipes.  In these instances a valve lockout device may need to be used.  These devices include pressurized gas valve lockout devices, rotating gate valve lockout devices, and wedge style ball valve lockout devices, among others.   Pressurized gas valve lockout devices protect the worker by physically surrounding the handle of a gas valve.  This prevents an employee from turning the handle of the gas valve.  Physically preventing the opening of the gas valve can be effective because it does not require any additional action on the behalf of the employee – the valve simply will not turn while the lock is in place.  This can help reduce the risk of death or injury because the worker will be aware that the valve is in a lockout position and should not tamper with the device.  These lockout devices are available in a wide variety sizes to best fit the needs of the situation. 

Rotating gate valve lockouts surround the operating handle in a spherical motion.  Although the mechanism of these devices is similar to that of the pressurized gas valve lockout devices, they are used to halt rotating parts rather than to prohibit the release of pressurized gases.  Outward and inward rotation is present on all rotating gate valve lockouts to ease the installation process and once in place these devices can be secured with a padlock.  Rotating gate valve lockout devices can be single use or used for group lockout systems.

Wedge style ball valve lockout devices secure valves in the “off” position and do not allow for the valve to be turned until the lock is removed.  This is once again similar to the mechanisms mentioned previously because the devices physically prevent the handle from being turned; however, the unique shape of this device allows for its use when previously mentioned devices may not be suitable.  Varied sizes exist to accommodate for varied valve diameters.

(Photo courtesy of ELCOSH)

LOTO for Mechanical Hazards

Mechanical hazards are present when power is given to a machine or tool.  Mechanical hazards are commonly found at the point of operation, the point of power transmission, as well as any area where moving parts are present.  Lockout situations for mechanical hazards may be the most commonly thought of lockout/tagout situations.  Mechanical hazard lockout devices include padlocks, pneumatic lockouts, and electrical plug lockouts, among others.    

Pneumatic and plus lockout devices surround equipment plugs to prevent an employee from plugging these pieces into a power source.  Once closed around the plug, a padlock will secure the device and prevent any unauthorized opening.  These devices are effective because the equipment is not able to be plugged in, and therefore must remain de energized until the lockout procedure is over. 


Although tagout devices are not thought to be as protective, they can be used in situations where lockout devices are not feasible. Tags or other warning devices are examples of tagout devices, and warn workers that the equipment or machinery is not to be used until they are removed. It is important to note that these devices do not de-energize the equipment, so a risk of the equipment being energized still exists.  This is the reason lockout is preferred over tagout in all situations where lockout is feasible. 


All workers should be trained in proper lockout/tagout procedures, as well as when it is required to use these procedures. OSHA states that: “The employer shall establish a program consisting of energy control procedures, employee training and periodic inspections to ensure that before any employee performs any servicing or maintenance on a machine or equipment where the unexpected energizing, startup or release of stored energy could occur and cause injury, the machine or equipment shall be isolated from the energy source and rendered inoperative.”

The lockout/tagout standard applies if:

  1. The worker must go around, or take off, a machine guard during non-routine production operations.
  2. While operating, the equipment or machine creates an area that could be dangerous to workers.
  3. The workers must come in close contact with the equipment or machinery at a point on the machine where material is being processed.

The types of energy that must be controlled include: electric, hydraulic, pneumatic, mechanical, heat, and pressurized liquids, vapors, and gases. All energy sources have the ability to unexpectedly start-up and therefore need to be de-energized prior to any servicing. Equipment or machinery may utilize more than one type of energy source and each source is required to have its own lockout device to prevent start-up.

A typical lockout/tagout procedure is listed below:

  1. All employees working with or near the equipment or machinery must be notified that it will be de-energized, and thus without power, prior to any de-energizing.
  2. The worker authorized to de-energize the equipment must ensure that he/she knows the proper way to shut down the device. This may require the use of a written procedure or manual that should be located on-site.
  3. The equipment should be properly shut down.
  4. Shutdown of the equipment must occur correctly.
  5. A lockout or tagout device should be placed on each energy source on the equipment or machinery to ensure it remains de-energized throughout the duration of the task.
  6. A unique lockout or tagout device for each employee working with the equipment or machinery must be used.

Individual lockout/tagout can occur as well as group lockout/tagout. When group lockout/tagout takes place, the equipment must remain de-energized until all workers involved with the equipment have removed their own lockout devices. Each individual working with the equipment is required to use their own unique lockout device that only they are able to remove. This will help to reduce an unexpected start-up of the equipment because each worker involved with the equipment will have removed their device prior to energizing.

Note: It is crucial to note that all individuals are required to have a personal and unique lockout device that only they are authorized and able to remove. This will help to ensure safety because each individual involved with the energy will be involved in the lockout procedure.

Risks Addressed:

Death or serious injury can result if a worker is unexpectedly exposed to energized equipment.

How Risks are Reduced:

Locks and tags can reduce the risk of electrocution, crushing, dismemberment, or other serious injuries or death by preventing unexpected equipment energization or unexpected release of machinery's stored energy.

Safety and health experts believe there is a great reduction in the risk of electrocution when proper LOTO devices are used. LOTO devices effectively prevent accidental equipment or machinery start-up maintaining it in a de-energized state. 

Brady reports that their lockout devices help employees avoid electrical incidents by providing devices that cover a wide range of mechanical and electrical applications. The devices provided by Brady are designed to promote optimum safety, maximize efficient, and reduce downtime in the workplace.

Grainger claims that lockout devices restrict access and maintain safety when servicing machines or de energizing electrical systems.

Studies have shown an association between proper lockout/tagout procedures and a reduction in the number of electrocutions that occur in the workplace. Research conducted by the National Institute for Occupational Safety and Health has shown that worker injuries and deaths could be prevented by using safe work practices, including proper lockout/tagout procedures.

Safety and health experts believe there is a risk reduction of electrocution when proper LOTO devices are used because the devices will effectively de energize the equipment or machinery being used, to reduce the likelihood of an accidental start-up.

Effects on Productivity:

When workers have an increased sense of safety, they may be more productive in the workplace.  By following proper and effective lockout/tagout procedures, workers may feel more safe while performing non-routine production operations and they may also be more productive due to this safe feeling.

Additional Considerations:

Turning off a power switch is not enough to effectively eliminate the risk to workers.  The machinery must be de-energized and locked out so that the equipment is prevented from starting while in the presence of the worker.  The worker must also check to ensure the energy is off prior to maintenance.  Many incidents that occur due to improper lockout/tagout procedures occur inadvertently. 

Each worker involved in maintaining the machine should utilize their own lockout device that only they can lock and unlock.  This should be done to help ensure the safety of all workers because each worker will be removed from the hazardous situation when they remove their lock.  This device should clearly state the individual’s name to which it belongs to ensure the correct individual removes the lock.  It is also important to test the machinery to ensure all tools, mechanical restraints, and electrical devices have been removed before the machine is re-energized. 

Shift changes should also be considered when assessing the use of lockout/tagout devices.  When a shift change occurs, the exiting personnel should meet the oncoming personnel at the lockout/tagout device.  The oncoming personnel should place their lockout devices on the machinery before the exiting personnel remove their devices to ensure safety of all individuals.

Here is an example of a lockout/tagout checklist: (page 4 of link)


It is also important to note that each piece of equipment being used must have its down lockout/tagout procedure.  General procedures exist, and should be followed before machine specific procedures.


Coffield, Lindsey and Fullen, Mark D., EdD, CSP - West Virginia University


Master Lock Safety Solutions
To obtain information, visit Lockout Tagout Devices or contact https://contact.masterlock.com/index.aspx?ID=33

Grainger Lockout Devices
To obtain information, visit Cable Lockout Devices and Circuit Breaker Lockout Devices and Pneumatic Lockout Devices or contact 1-800-472-4437

NIOSH Workplace Solutions Sheet
The National Institute of Safety and Health (NIOSH) has published a series of “Workplace Solutions”, which are easy-to-understand recommendations from NIOSH research results. Related to this Construction Solution, please find more information on: Using Lockout and Tagout Procedures to Prevent Injury and Death during Machine Maintenance

Brady Worldwide, Inc.
To obtain information, visit Electrical System Lockout Devices and Piping Lockout Devices and Padlocks and Tagout Devices or contact 1-888-250-3082

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