What Lockout/Tagout Means
Lockout/tagout, commonly abbreviated as LOTO, refers to procedures used to control hazardous energy while machinery or equipment is being serviced or maintained.
Turning off a machine is not always enough to make it safe. Equipment may still contain electrical power, hydraulic pressure, compressed air, heat, stored mechanical force, gravity, or another form of energy capable of causing unexpected movement or release.
A properly designed hazardous-energy control process helps prevent machinery from unexpectedly starting or stored energy from being released while someone is working on the equipment.
In U.S. general industry, OSHA’s primary standard addressing the control of hazardous energy is 29 CFR 1910.147. The standard establishes minimum performance requirements for controlling hazardous energy during covered servicing and maintenance activities. OSHA 29 CFR 1910.147 Lockout/Tagout Standard
Why Simply Pressing Stop Is Not Enough
A normal machine control button is designed to operate equipment, not necessarily to isolate energy. Even when a machine has stopped moving, its energy sources may remain connected.
A conveyor may retain electrical energy. Hydraulic equipment may remain pressurized. A raised component may be capable of falling under gravity. A flywheel may continue moving after power is turned off.
LOTO addresses these conditions by requiring energy to be isolated and controlled rather than relying only on operating controls.
Hazardous Energy Comes in Many Forms
OSHA identifies electrical, mechanical, hydraulic, pneumatic, chemical, thermal, and other energy sources as potentially hazardous. A single machine can contain several forms at the same time.
This is why energy-control procedures should be specific enough for authorized workers to understand the sources involved and how they will be safely isolated.
Lockout Versus Tagout
Lockout generally involves placing a lockout device on an energy-isolating device so that the isolating device and equipment cannot be operated until the lock is removed according to the established procedure.
Tagout uses a prominent warning device to indicate that the energy-isolating device and controlled equipment must not be operated until the tag is removed.
Under OSHA’s general-industry rule, when an energy-isolating device is capable of being locked out, lockout is generally required unless the employer can demonstrate that a tagout system provides full employee protection as specified by the standard.
A tag should therefore not be viewed as automatically equivalent to a physical lock. OSHA’s standard contains specific requirements for situations where tagout is used. OSHA Lockout/Tagout Program Resources
When Lockout/Tagout Is Relevant
OSHA’s general-industry LOTO standard applies to covered servicing and maintenance of machines and equipment when unexpected energization, startup, or release of stored energy could injure employees.
Activities can include inspecting, modifying, adjusting, lubricating, cleaning, unjamming, maintaining, or servicing machinery when the conditions fall within the standard’s scope.
Normal production operations are generally treated differently, although servicing performed during production may be covered in certain circumstances, including when an employee must remove or bypass a guard or other safety device or place part of the body into a hazardous area under conditions addressed by the standard.
Machine Guarding and LOTO Serve Different Purposes
Machine guarding primarily protects workers from hazardous machine components during operation. LOTO controls hazardous energy during covered servicing and maintenance activities.
Both can be essential parts of an industrial safety program. For a broader look at machinery and other risks, see our article on common manufacturing safety hazards.
Basic Elements of an Energy-Control Process
Exact procedures depend on the machinery and energy involved, but OSHA’s standard establishes a sequence for applying energy control.
Preparation and Shutdown
Before shutdown, the authorized employee needs knowledge of the type and magnitude of the energy, the hazards involved, and the method of controlling it. The machine is then shut down using established procedures.
Energy Isolation
Energy-isolating devices needed to control energy to the equipment are located and operated so the equipment is isolated from its energy sources.
Application of Devices
Authorized employees apply the required lockout or tagout devices to energy-isolating devices according to the procedure.
Control of Stored Energy
Residual or stored energy must be relieved, disconnected, restrained, or otherwise rendered safe. If hazardous energy could reaccumulate, continued verification may be necessary.
Verification
Before servicing begins, the authorized employee verifies that isolation and de-energization have been accomplished.
Why Verification Is Critical
Verification is one of the most important parts of an energy-control procedure because placing a lock on a disconnect does not by itself prove that every relevant source has been isolated.
Complex machinery may contain multiple energy sources, hidden circuits, stored pressure, interconnected equipment, or energy that can reaccumulate.
The specific method used to verify isolation depends on the equipment and hazards. It should be incorporated into the facility’s established energy-control procedure.
Authorized and Affected Employees
OSHA distinguishes between authorized employees and affected employees under the LOTO standard.
An authorized employee locks out or tags out equipment in order to perform covered servicing or maintenance. An affected employee operates or uses equipment being serviced or works in an area where the servicing is taking place.
The required knowledge differs because their roles differ. Authorized employees need training in recognizing applicable hazardous-energy sources and understanding the type and magnitude of the energy and the methods used to isolate or control it.
Affected employees need instruction concerning the purpose and use of the energy-control procedure, including restrictions on restarting or re-energizing locked or tagged equipment.
Group Lockout/Tagout
Industrial maintenance frequently involves multiple employees, departments, trades, or contractors. OSHA addresses group lockout/tagout situations and requires procedures that provide employees with protection equivalent to the use of a personal lockout or tagout device.
Group procedures need clear responsibility, coordination, and accountability, especially during shift changes or when the scope of work changes.
Outside Contractors and LOTO
Contract maintenance creates another coordination challenge. OSHA’s standard requires the on-site employer and outside employer to inform each other of their respective lockout or tagout procedures when outside servicing personnel perform activities covered by the rule.
The goal is to prevent assumptions about who controls equipment and how energy isolation is being managed.
Common LOTO Weaknesses
Problems can arise when procedures do not reflect actual machinery, when new equipment is added without updating documentation, or when employees rely on informal practices because a task is considered quick or routine.
Other weaknesses can include overlooking secondary energy sources, failing to control stored energy, poor contractor coordination, incomplete training, and inadequate verification.
Technology may increasingly assist with monitoring and documentation, but digital tools do not automatically replace physical energy-control requirements. For related developments, see how AI is changing workplace safety.
Periodic Inspection and Training Matter
OSHA requires employers covered by the standard to establish an energy-control program consisting of procedures, employee training, and periodic inspections.
Periodic review helps identify whether procedures remain accurate and whether employees are following them correctly. This becomes particularly important when machinery is modified, production layouts change, or new energy sources are introduced.
Why Lockout/Tagout Remains Important in 2026
Industrial equipment is becoming increasingly automated, connected, and software controlled, but the fundamental danger of uncontrolled energy remains.
In June 2026, OSHA publicly identified lockout/tagout modernization among its active regulatory priorities and indicated that it was examining the ANSI standard as a possible approach. That does not replace the currently applicable OSHA requirements, but it demonstrates that hazardous-energy control remains an active safety-policy issue. OSHA 2026 ASSP Regulatory Update
Final Thoughts
Lockout/tagout is important because machinery that appears stopped can still contain enough energy to seriously injure or kill a worker. Effective energy control requires identifying hazardous energy, isolating it, controlling stored energy, applying appropriate devices, and verifying that equipment is safe before covered servicing begins.
LOTO works best when it is treated as a practical part of equipment design, maintenance planning, employee training, and everyday safety management rather than a paperwork exercise.
As manufacturing becomes more automated, ensuring that employees can safely isolate increasingly complex equipment will remain a central part of industrial workplace safety.