The LOTO control procedure (Lockout/Tagout) is a standardized set of steps used to ensure that machines and energy sources are completely isolated, de-energized, and secured before maintenance or service work begins. It is a legal requirement under OSHA’s Control of Hazardous Energy standard (29 CFR 1910.147) in the United States and equivalent regulations in many other countries.
Why LOTO Exists: The Hazard of Stored Energy
Many workplace injuries occur when a machine unexpectedly starts up or releases stored energy while an employee is performing maintenance. Common energy sources include electrical, mechanical, hydraulic, pneumatic, chemical, thermal, and gravitational (e.g., a raised press). The LOTO procedure prevents these accidents by physically locking the energy-isolating device (like a circuit breaker or valve) in the safe position and attaching a tag to warn others. Without a formal procedure, a worker could be crushed, burned, electrocuted, or struck by a moving part.
Step-by-Step LOTO Procedure
OSHA requires a specific sequence for a proper lockout. Here is the standard procedure, which must be followed in order:
- Notify affected employees: Tell everyone who operates the machine or works nearby that maintenance will occur and the equipment will be shut down.
- Shut down the equipment: Use the normal stop button or switch to bring the machine to a complete and safe stop.
- Isolate the energy source: Operate the disconnect switch, valve, or other energy-isolating device so that energy is no longer flowing to the equipment.
- Apply the lock and tag: Place your personal lock on the isolating device and fill out and attach a tag with your name, date, and reason. Only the person who applied the lock has the key to remove it.
- Release or restrain stored energy: Check for any stored energy (e.g., capacitors, springs, compressed air, elevated parts) and safely discharge or block it. This may involve bleeding pressure lines, grounding capacitors, or installing support blocks.
- Verify isolation: Try to start the machine using the normal controls. It should not operate. Then return the controls to the “off” position. This step confirms the lockout is effective.
When a LOTO Procedure Is Required
LOTO is required for any activity where an employee could be exposed to the unexpected energization or startup of equipment, or the release of hazardous energy. This includes:
- Repairing or replacing parts
- Clearing jams or blockages
- Lubricating or adjusting machinery
- Cleaning equipment when guards must be removed
- Inspecting or testing where machine parts could move
However, there are exceptions. For example, if a task is considered “minor tool changes” or “adjustments” that are routine and the machine has no exposed moving parts, LOTO may not be required. Also, if the maintenance is performed by a single employee who is in full control of the energy source and the machine is cord-and-plug connected, a simple unplugging may suffice—but only if the plug is under the employee’s exclusive control.
Group Lockout and Contractor Coordination
When multiple employees work on the same equipment, each person must apply their own personal lock to a group lockout device (often a hasp that can hold several locks). This ensures no one can be exposed to energy because one person left early. The employer must also coordinate with outside contractors. If a contractor works on a machine that the host employer’s employees also service, both must agree on a single lockout procedure and follow it consistently. Typically, the host employer provides the primary lockout, and the contractor adds their locks.
Common LOTO Mistakes and How to Avoid Them
Even with a written procedure, mistakes happen. The most frequent errors include:
- Skipping the verification step: Always try to restart the equipment after locking out. This is the only way to be sure the isolation is complete.
- Using tags alone: A tag is not a physical barrier. OSHA requires a lock whenever the energy-isolating device can accept one. Tags are only allowed when a lock cannot be attached, and then additional precautions are needed.
- Removing someone else’s lock: Never remove another person’s lock without their knowledge. If a shift change occurs, the outgoing worker must remove their lock and the incoming worker must apply their own before work continues.
- Not accounting for all energy sources: A machine may have both electrical and pneumatic connections. Failing to isolate all sources leaves a hidden hazard.
LOTO Training and Audits
OSHA requires that all employees who perform maintenance under LOTO receive training. There are three levels: authorized employees (who apply locks), affected employees (who operate the equipment), and other employees (who may be near the equipment). Training must cover recognition of hazardous energy, the purpose and function of the lockout program, and the specific procedures for each machine. Employers must also conduct periodic inspections of the LOTO procedure at least annually. During an inspection, an authorized employee performs the lockout while a supervisor observes to ensure the steps are followed correctly. Any deviations must be corrected and documented.
LOTO Procedure Template
Equipment: ____________________ Location: ____________________
Energy sources to isolate: ☐ Electrical ☐ Mechanical ☐ Hydraulic ☐ Pneumatic ☐ Chemical ☐ Thermal ☐ Other: ____________
Steps:
- Notify: ____________________
- Shutdown: ____________________
- Isolate: ____________________
- Lock and tag: ____________________
- Release stored energy: ____________________
- Verify: ____________________
Authorized employee: ____________________ Date: ____________
Sample (fictional): Equipment: Conveyor Belt #3 Location: Warehouse A Energy sources: Electrical (breaker #7), Pneumatic (air valve #2) Steps: Notify shift supervisor; press stop button; open breaker #7 and air valve #2; apply personal lock #42 and tag; bleed air line; press start button—no movement. Authorized: J. Smith Date: 2025-03-14
Frequently Asked Questions
What is the difference between lockout and tagout?
Lockout uses a physical lock to hold an energy-isolating device in a safe position, preventing the machine from being energized. Tagout uses a warning tag but does not physically prevent operation. OSHA requires lockout whenever the device can accept a lock; tagout is only allowed when a lock cannot be attached, and then the tag must be accompanied by additional safety measures.
Can an employee remove their own lock at the end of a shift?
Yes, but only after the machine is verified safe and the work is complete. If the work is not finished, the employee must remove their lock and the incoming employee must apply their own before leaving. This is part of a shift-change procedure that must be documented in the LOTO program.
Do I need a LOTO procedure for a simple plug-in tool?
If the tool is cord-and-plug connected and the plug is under the exclusive control of the employee performing the maintenance, unplugging it is sufficient—no lock is required. However, if the plug is not under exclusive control (e.g., another person could plug it back in), a lock must be used.
What should I do if I see someone working on a machine that is not locked out?
Stop immediately and warn the person. If you are an authorized employee, do not approach the machine; instead, notify your supervisor or safety officer. Do not attempt to remove a lock or tag that is not yours. This is a serious safety violation that should be reported and corrected.
How often must LOTO training be repeated?
OSHA does not specify a frequency for retraining, but it must be provided whenever a job assignment changes, a new machine or energy source is introduced, or a new procedure is implemented. Additionally, if an audit reveals a deviation, retraining is required. Many employers choose to retrain annually to stay compliant.