LOTOTO stands for lockout, tagout, and tryout. OSHA formally regulates this work as lockout/tagout, but the verification behind “tryout” is not optional: before servicing begins, the authorized employee must verify that isolation and deenergization have been accomplished. That affirmative check confirms that the preceding energy-control steps have effectively isolated the machine or equipment.
Key Takeaways
- Lockout, Tagout, and Tryout (LOTOTO) procedures are essential for preventing accidents by isolating hazardous energy before maintenance.
- Identifying and isolating all energy sources, including secondary ones, is critical to avoid unexpected equipment activation.
- Hazardous energy must first be isolated through the appropriate energy-isolating devices; lockout tagout devices are then applied under the energy control procedure to maintain control of those isolation points.
- Following an equipment-specific energy control procedure helps authorized employees shut down equipment, isolate hazardous energy, apply energy-control devices, control stored energy, and verify isolation before servicing.
- The tryout step in LOTOTO is a key safety practice in verifying the proper implementation of lockout procedures.
What Is LOTOTO?
Most people in the industry are familiar with lockout/tagout, or LOTO, but may not recognize the expanded term LOTOTO. Both refer to controlling hazardous energy before servicing or maintenance. LOTOTO adds the word “tryout” to emphasize a verification step that is already required within an OSHA-compliant lockout/tagout procedure.
LOTOTO stands for Lockout, Tagout, and Tryout. The first two terms describe the application of energy control devices under an established procedure. The tryout step confirms that isolation and deenergization have been accomplished before work begins.
Lock Out
In a lockout, a device specifically used for energy control procedures is placed on the energy isolating device, such as a valve, switch, or circuit breaker in accordance with a specific procedure. The primary purpose of a lockout, as noted by OSHA’s Control of Hazardous Energy standard, is to ensure that the energy-isolating device and the equipment being controlled cannot be operated until the lockout device has been removed.
Tag Out
Tagout is the placement of a tagout device on an energy-isolating device under an established procedure. The tag warns that the energy-isolating device and controlled equipment must not be operated until the tag is removed.
A tag may accompany a lock under an employer’s energy control procedure, but tagout is not simply a labeling step that always follows lockout. When a tagout system is used instead of lockout on equipment capable of being locked out, the employer must provide full employee protection equivalent to a lockout system and use additional safety measures as needed.
Try Out
The tryout or verification step involves testing controls and attempting to operate the equipment after applying a LOTO procedure. OSHA’s lockout tagout toolbox talk noted that this procedure tests if the machinery and equipment have been properly locked out.
In traditional LOTO procedures, the focus is on de-energizing and locking out the equipment, with safety tags indicating that it is not to be operated. However, in LOTOTO, after the equipment is locked out and tagged, the tryout phase involves actively testing the machinery to confirm that it cannot be reactivated. This ensures that all sources of energy have been effectively isolated, offering an additional layer of safety verification before work begins.
Importance of LOTOTO in Energy Isolation
Industrial equipment can contain several forms of hazardous energy. Common sources include:
- Electrical Energy – Power stored in electrical circuits or systems. If not isolated, electrical energy can cause shocks, burns, or even electrocution.
- Mechanical Energy – Energy stored in moving parts such as gears, springs, or rotating shafts. Uncontrolled release of mechanical energy can result in crushing, cutting, or entanglement.
- Hydraulic and Pneumatic Energy – Pressure from liquids (hydraulic) or gases (pneumatic) can cause significant harm if released unexpectedly. Hydraulic systems, for example, store energy in pressurized liquids that can cause sudden and forceful movements.
- Thermal Energy – Equipment like boilers, furnaces, or pipes may retain heat or cold, posing burn or freeze hazards.
- Chemical Energy – Chemicals stored under pressure or in reactive states can cause explosions, fires, or toxic exposures if not properly contained.
The incidents described earlier show why applying locks and tags is not the final check. OSHA requires the authorized employee to verify that isolation and deenergization have been accomplished before work begins. This check can identify a missed energy source, an ineffective isolation point, stored energy, or another condition that could expose workers during servicing.
Below are the other reasons why LOTOTO is important:
- Verifying Stored-Energy Controls: Verification confirms that potentially hazardous stored or residual energy has been relieved, disconnected, restrained, or otherwise rendered safe.
- Checking Isolation Effectiveness: Depending on the equipment and energy source, verification may include attempting normal operating controls, visual inspection, or appropriate testing. An attempted start alone does not verify every form of hazardous energy.
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Confirming the Condition Before Work Begins: Servicing should not begin until the authorized employee has verified that isolation and deenergization have been accomplished.
Standards and Regulations on LOTOTO Procedures
OSHA does not use LOTOTO as the formal name of a separate standard. However, verification is not optional under the Control of Hazardous Energy standard. Before work begins, 29 CFR 1910.147(d)(6) requires the authorized employee to verify that isolation and deenergization have been accomplished.
- OSHA 1910.147 - Establishes general-industry requirements for controlling hazardous energy during servicing and maintenance, including energy control procedures, training, stored-energy control, and verification of isolation.
- ANSI/ASSP Z244.1-2024 - Establishes consensus requirements for controlling hazardous energy through lockout, tagout, and alternative methods.
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NFPA 70E-2027 - Addresses electrical safety-related work practices, including requirements for establishing and verifying an electrically safe work condition.
Basic Components of LOTOTO
LOTOTO Policy
Employers covered by OSHA 1910.147 must establish an energy control program consisting of energy control procedures, employee training, and periodic inspections. The program should clearly define the responsibilities of authorized, affected, and other employees and be implemented consistently across covered servicing and maintenance work.
LOTOTO Training
OSHA training requirements depend on each employee’s role. Authorized employees must be trained to recognize applicable hazardous energy sources and understand the methods needed for isolation and control. Affected employees must be instructed in the purpose and use of the energy control procedure, while other employees working in the area must understand the procedure and the prohibition against restarting or reenergizing locked-out or tagged-out equipment.
Training for authorized employees should cover the complete equipment-specific process, including how isolation is verified before servicing begins. The employer must also provide retraining when job assignments, equipment, processes, or energy control procedures change, or when an inspection identifies gaps in an employee’s knowledge or use of the procedure.
Here is an overview of the key topics that should be covered in a comprehensive LOTOTO training program:
- Understanding Hazardous Energy Sources: Employees must be trained to identify different types of hazardous energy and understand where these energy sources exist in the workplace as well as the risks they pose during maintenance.
- LOTOTO Procedures and Steps: Training should cover the full Lockout Tagout Tryout (LOTOTO) process, from preparation to tryout. Workers must know how to identify energy sources, properly shut down equipment, and perform the tryout to verify isolation.
- Lockout Devices and Their Use: Employees should be trained on how to use different lockout devices like locks, chains, and valve covers. The training must emphasize secure application to prevent tampering or accidental removal.
Tryout Step for Verifying Isolation
The tryout process varies depending on the type of equipment and the nature of the energy source. Workers should be trained in verifying isolation for the following:
- Electrical Equipment: Where employees will be exposed to deenergized electrical circuit parts covered by 29 CFR 1910.333, a qualified person must operate the equipment controls or otherwise verify that it cannot be restarted and use appropriate test equipment to verify deenergization, including checking for induced or backfeed voltage.
- Mechanical Equipment: Verify that hazardous motion and stored mechanical energy have been blocked, restrained, released, or otherwise rendered safe using the method specified in the equipment-specific procedure.
- Hydraulic and Pneumatic Systems: Bleed, block, restrain, or otherwise control stored pressure, then verify the condition using the procedure-specified method. If hazardous pressure can reaccumulate, continue verification as necessary.
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Thermal Energy: Verify that hazardous thermal energy has been controlled or rendered safe to the level required by the equipment-specific procedure before work begins.
Steps in Implementing LOTOTO Procedures
1. Prepare
Before beginning the LOTOTO process, workers must understand the specific hazards associated with the equipment and the types of energy involved. This includes identifying all energy sources, such as electrical, mechanical, hydraulic, or thermal energy, and determining how to isolate them. Workers should also review the energy control procedure and ensure that all required paperwork, permits, and scheduling are in place.
2. Notify
Notify all affected employees and individuals that the equipment will be locked out or isolated. Employees must be instructed to stay away from the equipment and be reminded not to attempt to energize or operate it while it is locked out. Clear communication during this phase prevents accidental start-up and ensures that no one is placed at risk during the maintenance or repair task.
3. Shutdown
The shutdown process must follow the specific energy control procedure for the equipment. Workers should use the standard operating controls to safely and systematically shut down the machine. It is important that this step is performed in an orderly and controlled manner to avoid creating new hazards, such as sudden equipment movement or pressure build-up
4. Isolation
Using appropriate isolation points, isolate the machine or equipment from hazardous energy. Also, isolate secondary energy sources that might interfere with the isolation procedure. In case of electrical defects, isolate the equipment through its energy isolation devices, not with its controls.
5. Apply locks and tags
Once the energy-isolating devices have been operated, apply lockout or tagout devices as required by the employer’s energy control procedure. If an energy-isolating device is capable of being locked out, OSHA requires lockout unless the employer can demonstrate that a tagout system provides full employee protection. Group lockout must provide protection equivalent to personal lockout, and each authorized employee must affix a personal lockout or tagout device to the group lockout device, group lockbox, or comparable mechanism when work begins. A warning tag may accompany a lock if the employer’s procedure calls for it, but OSHA does not require a tag to accompany every lockout device.
6. Zero Energy State
After lockout or tagout devices are applied, all potentially hazardous stored or residual energy must be relieved, disconnected, restrained, or otherwise rendered safe. Depending on the equipment, this may include bleeding pressure, discharging capacitors, blocking elevated or moving parts, or restraining springs. If hazardous energy can reaccumulate, verification must continue until servicing is complete or reaccumulation is no longer possible.
7. Tryout
After hazardous energy has been isolated and stored energy has been rendered safe, the authorized employee must verify isolation and deenergization before work begins. Follow the equipment-specific procedure, which may require trying normal operating controls and using an appropriate test method or instrument for the energy involved. If the equipment responds or hazardous energy is detected, stop and correct the isolation before testing again. Return operating controls to the neutral or off position after the attempt.
8. Perform task
Start and complete the planned task, such as maintenance and repair, while following safety protocols and procedures. In the event of accidental re-energization or other unexpected hazards, the task should be immediately stopped, all workers should withdraw, and control measures must be re-implemented. Near hits or accidents should be reported and investigated to identify what went wrong and to improve safety protocols for the future.
9. Inspect and restore
After servicing is complete, inspect the machine, equipment, and surrounding work area to confirm that nonessential items have been removed, components are operationally intact, and employees are safely positioned or clear. Each lockout or tagout device must normally be removed by the employee who applied it; removal by another person is permitted only under the employer’s documented exception procedure.
After the devices have been removed and before the machine or equipment is started, notify affected employees. Restore energy and return the equipment to service in accordance with the established procedure, then complete any required records or permits.
Watch the TRADESAFE step-by-step guide for a visual explanation of the lockout, tagout, and tryout process.
Go home safe today: Lock, Tag, and Try
Verification is the final check before servicing begins. It confirms that the selected isolation and stored-energy controls are effective for the machine and the work being performed. Help your employees go home safely today. Lock, tag, and try.
FAQs
What does LOTOTO mean?
LOTOTO means lockout, tagout, and tryout. The added “tryout” emphasizes verifying that energy isolation and deenergization are effective before servicing begins. OSHA regulates this work under its lockout/tagout standard rather than a separate LOTOTO standard.
Is the tryout step required by OSHA?
OSHA requires an authorized employee to verify isolation and deenergization before work begins under 29 CFR 1910.147(d)(6). The standard does not require employers to call this step “tryout,” but the verification itself is required for covered work. The method must match the machine, energy sources, and equipment-specific procedure.
What is the difference between LOTO and LOTOTO?
LOTO is the standard term for lockout/tagout, while LOTOTO adds “tryout” to emphasize verification. LOTOTO is not a separate OSHA standard or a replacement for LOTO. Verification is already part of a compliant OSHA lockout/tagout procedure.
Who performs verification before servicing begins?
Under OSHA 1910.147(d)(6), the authorized employee verifies that isolation and deenergization have been accomplished. Affected employees and other employees have different instruction and notification responsibilities. The employer’s energy control procedure should identify who performs each step.
What should happen if equipment responds during the tryout?
Do not begin servicing if the equipment starts, moves, produces pressure, shows voltage, or otherwise indicates hazardous energy. Stop and correct the isolation or stored-energy control before repeating the verification. Work should begin only after the equipment-specific procedure confirms an effective energy-isolated condition