Lockout/Tagout (LOTO)
Control of hazardous energy — OSHA's #6 most-cited standard and a cornerstone of workplace safety
The practice of physically isolating and securing energy sources before servicing or maintaining equipment — preventing unexpected startup that can maim or kill.
What Is Lockout/Tagout?
Lockout/Tagout (LOTO) is the practice of physically isolating and securing every energy source on a piece of equipment before any employee performs servicing or maintenance. A lock physically prevents an isolation device — a circuit breaker, a valve, a disconnect switch — from being moved to the “on” position. A tag warns other workers that the equipment is being serviced and must not be re-energized. Together, they create a barrier between the worker and the stored or supplied energy that could otherwise cause catastrophic injury.
The governing regulation is 29 CFR 1910.147 — The Control of Hazardous Energy (Lockout/Tagout). It is one of the most important and most frequently cited OSHA standards in general industry. Compliance is not optional; it is a life-safety requirement.
Why LOTO Matters
By the numbers: Unexpected energization or the release of stored energy causes approximately 120 fatalities and 50,000 injuries per year in the United States. Workers who service equipment without proper LOTO procedures face electrocution, amputation, crushing, burns, and chemical exposure. LOTO is consistently in OSHA's top 10 most-cited standards, typically ranking between #4 and #8 depending on the year.
Proper LOTO procedures are estimated to prevent 120 fatalities and 50,000 injuries annually. OSHA considers failures in hazardous energy control so serious that willful violations can carry penalties exceeding $150,000 per instance. Beyond compliance, LOTO is the single most effective way to protect maintenance workers from the equipment they service.
Scope and Applicability
29 CFR 1910.147 applies to general industry. Construction has parallel requirements under 29 CFR 1926 Subpart K (Electrical) and general duty clause obligations for non-electrical energy. The standard covers the servicing and maintenance of machines and equipment where unexpected energization or the release of stored energy could harm employees.
The standard does NOT apply to:
- Normal production operations — unless the employee must remove or bypass a guard or safety device, or place any part of their body in a danger zone.
- Hot tap procedures — under specific conditions involving pressurized pipelines, when continuity of service is essential and documented procedures demonstrate equivalent safety.
- Cord-and-plug equipment — when the plug is under the exclusive control of the employee performing the work (i.e., the worker unplugs it and keeps the plug within sight and reach).
Types of Hazardous Energy
A complete LOTO procedure must address every form of energy associated with the equipment. Missing even one energy source can be fatal. The recognized types are:
The 8 Steps of Lockout/Tagout
OSHA guidance breaks the LOTO process into eight sequential steps. Skipping or reordering any step defeats the purpose of the procedure.
- Preparation — Identify all energy sources associated with the equipment. Review the machine-specific energy control procedure. Notify all affected employees that the equipment will be shut down and locked out.
- Shutdown — Perform an orderly shutdown of the equipment using the normal stopping procedure. Never simply pull a disconnect on a running machine unless it is an emergency.
- Isolation — Physically isolate ALL energy sources. Open disconnect switches, close valves, block fluid lines, disconnect pneumatic supply, and address every energy type identified in Step 1.
- Application of LOTO devices — Apply a lock and a tag to each energy isolation device. Each authorized employee applies their OWN lock. No sharing. No master keys for convenience. Tags must identify the employee, the date, and the reason for lockout.
- Release of stored energy — Dissipate or restrain all residual or stored energy. Discharge capacitors, relieve trapped pressure, lower elevated components to their rest position, block against movement from springs or gravity. This step is commonly missed and is a leading cause of LOTO-related fatalities.
- Verification — Before touching anything, attempt to start the equipment using the normal controls to confirm it is truly de-energized. Use appropriate test instruments — a voltage tester for electrical circuits, a pressure gauge for hydraulic/pneumatic lines. Never rely on the position of a switch alone.
- Perform the work — With all energy sources verified as isolated and secured, perform the servicing or maintenance task.
- Removal of LOTO — Re-energize in reverse order. Ensure all tools and personnel are clear. Remove locks and tags — only the employee who applied a lock may remove it (with narrow exceptions for employer-documented procedures when the employee is unavailable). Notify affected employees that the equipment is being returned to service.
Key OSHA Requirements
Written Energy Control Procedures
Employers must develop and document machine-specific energy control procedures. A single generic “blanket” procedure is permitted only when certain narrow conditions are met under 1910.147(c)(4)(i): the machine has no stored or residual energy after shutdown, has a single energy source that can be readily identified and isolated, the isolation fully de-energizes the machine, and the procedure is not shared among different machines with different energy profiles.
Locks vs. Tags
Locks are ALWAYS preferred. Tagout alone is permitted only when the energy isolation device is physically incapable of accepting a lock AND the employer can demonstrate that the tag program provides a level of safety equivalent to a lock AND additional training is provided to all employees. In practice, OSHA expects locks on virtually everything. If a device cannot accept a lock, retrofit it.
Individual Accountability
Each authorized employee applies their own personal lock. No shared locks, no master-key shortcuts. For multi-person (group) LOTO jobs, a primary authorized employee coordinates the procedure, but every worker on the job still applies an individual lock to a group lockbox or hasp.
Annual Inspection
Each machine-specific energy control procedure must be reviewed at least annually. The review must be conducted by an authorized employee who was NOT involved in the procedure being audited. The inspection must verify that the procedure and the requirements of 1910.147 are being followed. The employer must document the inspection, including the date, the equipment, the employees included, and the identity of the inspector.
Training Requirements
OSHA defines three tiers of employees, each requiring distinct training:
- Authorized employees — those who perform LOTO. Trained in recognition of applicable hazardous energy sources, the type and magnitude of energy, and the methods and means for isolation and control.
- Affected employees — those who operate or work near locked-out equipment. Trained in the purpose and use of LOTO procedures and the prohibition against attempting to restart locked-out equipment.
- Other employees — all other workers in the area. General awareness that LOTO is in effect and that they must not remove locks, tags, or attempt re-energization.
Retraining is required whenever there is a change in job assignments, a change in machines or processes that present new hazards, a change in energy control procedures, or when the employer has reason to believe that inadequacies exist in an employee's knowledge.
Common OSHA Citations
The following deficiencies account for the vast majority of 1910.147 citations year after year:
- No written energy control procedures — the #1 citation. Many employers have no documented procedure at all.
- Procedures not machine-specific — a single generic blanket procedure used for all equipment without meeting the exception criteria.
- Annual inspection not conducted or not documented — the review must happen, and it must be recorded.
- Tags used instead of locks without justification — employers default to tagout without demonstrating that lockout is impossible and that equivalent safety is achieved.
- Stored energy not verified as released — workers isolate the primary source but fail to bleed pressure, discharge capacitors, or block against gravity.
- Inadequate employee training — no initial training, no retraining after procedure changes, or no distinction between authorized, affected, and other employees.
References
1. 29 CFR 1910.147: The Control of Hazardous Energy (Lockout/Tagout). U.S. Department of Labor, OSHA.
2. 29 CFR 1926 Subpart K: Electrical (construction-industry energy control requirements).
3. ANSI/ASSP Z244.1-2016: The Control of Hazardous Energy — Lockout, Tagout, and Alternative Methods.
4. NFPA 70E (2024): Standard for Electrical Safety in the Workplace.
5. OSHA Fact Sheet: Lockout/Tagout. Publication 3120.
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Discussion (2)
Great breakdown of the technical details. The NFPA 25 maintenance table is exactly what I needed for my ITM schedule.
Really clear explanation. Would love to see a companion video walkthrough of the inspection process.