When equipment needs to be repaired, cleaned, inspected, or maintained, shutting it down is only the first step in making the work area safe. Even when a machine appears to be off, hazardous energy may still be present. Unexpected startup, the release of stored energy, or the movement of equipment can expose employees to serious injuries.
Lockout/Tagout (LOTO) procedures are designed to prevent these incidents by controlling hazardous energy before servicing or maintenance begins. Under OSHA's General Industry standard, 29 CFR 1910.147: The Control of Hazardous Energy, employers must establish an energy control program that includes procedures, employee training, and periodic inspections.
Yet having a written Lockout/Tagout program does not automatically mean employees are following it correctly. Small oversights, shortcuts, and misunderstandings can create dangerous gaps in an otherwise established safety process.
Understanding where these mistakes happen is an important step toward preventing injuries and maintaining a safer workplace.
One of the most common misconceptions about hazardous energy control is that turning off a machine is enough to make it safe to work on.
A machine's normal operating controls, such as a stop button, selector switch, or emergency stop, do not necessarily isolate it from its energy sources. Equipment may still be connected to electrical, hydraulic, pneumatic, mechanical, chemical, or thermal energy.
For example, a conveyor may be switched off but remain connected to its electrical supply. A hydraulic system may retain pressure, or a suspended component may still be capable of moving under gravity.
How to prevent this mistake:
Employees responsible for servicing or maintenance must identify all applicable energy sources and use the appropriate energy-isolating devices to disconnect equipment from those sources. Simply stopping equipment does not replace the required isolation process.
OSHA requires employers to establish specific procedures for shutting down, isolating, blocking, and securing equipment against unexpected energization or the release of stored energy. These requirements are outlined in OSHA's hazardous energy control standard.
Disconnecting equipment from its energy sources does not always eliminate every hazard.
Some machines and systems can retain energy even after they have been shut down and isolated. This is known as stored or residual energy, and it can be just as dangerous as an active energy source.
Examples include:
If stored energy is not properly released, disconnected, restrained, or otherwise made safe, employees may still be exposed to hazardous conditions even after locks and tags have been applied.
How to prevent this mistake:
Energy control procedures should identify potential sources of stored energy and explain how to safely relieve or restrain them. Employees must also account for the possibility that stored energy could build up again during the work.
OSHA requires authorized employees to address hazardous stored or residual energy after applying lockout or tagout devices. When energy could reaccumulate to a hazardous level, verification must continue until the work is completed or that possibility no longer exists. Additional information is available in OSHA's Lockout/Tagout Program guidance.
Applying a lock and tag is an important part of the Lockout/Tagout process, but it does not automatically confirm that equipment has been properly isolated.
Verification is the step that helps confirm the energy control measures are effective before work begins.
Skipping this step can leave employees exposed to unexpected startup, movement, or the release of hazardous energy. An isolation point may have been missed, a valve may not have fully closed, or another energy source may still be connected.
How to prevent this mistake:
Before servicing or maintenance begins, the authorized employee must verify that the equipment has been isolated and deenergized. This may include attempting to operate the equipment using its normal controls, when appropriate, or using testing equipment to confirm that energy has been eliminated.
Any normal operating controls used during verification must be returned to the neutral or off position afterward.
Verification should never be treated as an optional final check. It is a critical part of confirming that the energy control procedure has worked as intended. OSHA outlines these steps in 29 CFR 1910.147, including the requirements for testing and verifying energy control measures.
Lockout and tagout are often discussed together, but the two devices do not provide the same level of protection.
A lock physically holds an energy-isolating device in a safe position, helping prevent it from being operated. A tag communicates that the equipment must not be operated, but it does not physically prevent someone from moving a switch, opening a valve, or otherwise activating the equipment.
OSHA generally requires lockout when an energy-isolating device is capable of being locked out. A tagout system may be used when the device cannot be locked out. When a device can be locked out but an employer chooses to use tagout instead, the employer must demonstrate that the tagout system provides full employee protection equivalent to lockout, along with any additional protective measures required by the standard.
How to prevent this mistake:
Employers should make sure employees understand when locks and tags are appropriate and how each must be used. Lockout/tagout devices must also meet OSHA requirements for identification, durability, standardization, and appropriate use.
A tag should never be viewed as a substitute for a lock simply because it is easier or more convenient to apply.
For more information, see OSHA's requirements for lockout and tagout devices.
Not all machines and equipment present the same energy hazards. A procedure that works for one piece of equipment may not provide adequate protection for another.
Generic instructions that tell employees to shut down equipment, disconnect power, and apply a lock may leave out important details. Employees need to know which energy sources must be controlled, where the isolation points are located, and how stored energy should be addressed.
Procedures can also become outdated when equipment is replaced, modified, or relocated.
How to prevent this mistake:
Energy control procedures should be specific to the equipment and servicing activities they cover. They should clearly explain the steps required to shut down, isolate, block, and secure equipment, as well as how to apply and remove devices and verify that isolation has been achieved.
Employers should also review procedures whenever equipment, processes, or energy control methods change.
OSHA requires periodic inspections of energy control procedures at least annually, with each procedure inspected at least once during that period. These inspections help confirm that procedures remain accurate and that employees understand their responsibilities.
Employers can review the requirements in OSHA's hazardous energy control standard and find additional program resources through OSHA's Lockout/Tagout Program guidance.
Lockout/Tagout becomes more complicated when multiple employees, departments, or contractors are involved in the same maintenance activity.
For example, one employee may begin a repair before another employee joins the job. A shift may end while equipment remains locked out, requiring another employee to take over the work.
Without clear procedures, employees may misunderstand who is protected by the lockout, who is responsible for maintaining energy control, or when equipment can safely be returned to service.
How to prevent this mistake:
Employers should establish clear procedures for group lockout and changes in personnel or shifts.
When multiple employees are involved, group lockout procedures must provide a level of protection equivalent to each employee applying their own personal lockout or tagout device. Each authorized employee must be protected throughout the servicing or maintenance activity.
Shift changes also require an orderly transfer of lockout or tagout protection so that employees are not exposed to unexpected energization during the transition.
Communication is essential. Everyone involved should understand the status of the equipment, who is working on it, and what must happen before energy can be restored.
These responsibilities are addressed in OSHA 29 CFR 1910.147(f), which covers group lockout and shift or personnel changes.
Lockout/Tagout training is not one-size-fits-all. Employees have different responsibilities depending on their involvement with equipment and maintenance activities.
OSHA distinguishes between three primary employee categories:
Each group needs to understand the hazards and restrictions relevant to its responsibilities.
For example, an affected employee may not be responsible for applying a lock, but they must understand that equipment cannot be operated while it is locked or tagged out. Authorized employees need more detailed training on the energy sources, equipment-specific procedures, and proper application and removal of control devices.
How to prevent this mistake:
Training should reflect each employee's role and responsibilities. Employers must provide initial training and retraining when required by changes in job assignments, equipment, processes, or energy control procedures, or when inspections indicate that an employee's knowledge or use of the procedures needs improvement.
Employees should understand not only what Lockout/Tagout is, but also when it applies and what actions they are expected to take.
OSHA explains these training responsibilities in 29 CFR 1910.147(c)(7), Training and Communication.
Preventing Lockout/Tagout mistakes requires more than distributing locks, tags, and written procedures. Employers need a consistent program that employees understand and follow every time servicing or maintenance activities expose them to hazardous energy.
A strong program should include:
It is also important to remember that Lockout/Tagout is not a one-time training topic. Employees need opportunities to reinforce what they have learned and stay familiar with the procedures that apply to their work.
For additional information on developing and maintaining a hazardous energy control program, employers can explore OSHA's Control of Hazardous Energy resources.
Lockout/Tagout procedures are designed to prevent serious injuries caused by unexpected equipment startup or the release of hazardous energy. But their effectiveness depends on how consistently they are implemented.
A missed energy source, an outdated procedure, or a skipped verification step can put employees at risk. Taking the time to identify hazards, follow equipment-specific procedures, and verify isolation helps ensure that employees are protected before maintenance begins.
For employers, building a strong Lockout/Tagout program means making sure employees have the knowledge, resources, and training they need to do the job safely.
At Sentry Road, we believe effective safety training goes beyond checking a box. It helps employees recognize hazards, understand their responsibilities, and make safer decisions in the workplace.
Learn how Sentry Road can help strengthen your workplace safety training and compliance program at sentryroad.com.