Lockout tagout definition: what it means and why OSHA requires it

Last updated 2026-07-09

What is the definition of lockout tagout?

Lockout tagout is a safety procedure that cuts off every energy source feeding a machine, then keeps that machine from starting back up until the work is done and every worker is clear. "Lockout" means physically securing an energy-isolating device, usually with a padlock, so the machine cannot start. "Tagout" means attaching a warning tag to that same device when a lock cannot be used.

OSHA defines the practice at 29 CFR 1910.147, titled "The Control of Hazardous Energy (Lockout/Tagout)." The scope statement says it covers "the servicing and maintenance of machines and equipment in which the unexpected energization or startup of the machines or equipment, or release of stored energy, could cause injury to employees." ^[1]

That phrase "stored energy" is the part people miss. Cutting electrical power is only half the job. LOTO covers every form of energy a machine holds: electrical, pneumatic (compressed air), hydraulic, mechanical (springs under tension, gravity pulling on raised parts), thermal, and chemical. A press with a loaded spring can still crush your hand with the breaker off. A hydraulic cylinder can drop under its own weight. The standard makes you neutralize all of it, more than flip the main switch.

The shorthand "LOTO" runs through the trades. You'll also hear "energy control" or "energy isolation." Same idea every time. Before you put your hands inside a machine, you make certain nothing can move.

What does the OSHA lockout tagout standard actually require?

29 CFR 1910.147 has five core requirements for general industry employers. Get each one right and the definition turns into a working program.

A written energy control program. You have to document the overall procedures, rules, and techniques for controlling hazardous energy. This is the policy layer, not the machine-specific instructions. ^[1]

Equipment-specific procedures. Each machine needs a written procedure that names every energy source, the location of every isolating device, and the exact steps to follow. OSHA lets you use a single procedure for a group of machines only when those machines are identical in type, configuration, and energy sources. In practice, most shops need one procedure per machine.

Training. Every authorized employee (the person who performs the lockout) and every affected employee (someone who works where lockout is used) must be trained, and the standard spells out different content for each group. Retraining kicks in when there's reason to think the procedure isn't being followed or when job assignments change. ^[1]

Periodic inspections. At least once a year, a qualified person reviews the energy control procedures and confirms they're being followed. The inspection has to be certified in writing, with the date, the machines covered, the employees involved, and the name of the person doing the inspection. ^[1]

Hardware. Lockout devices have to be durable, standardized in color and shape, strong enough to resist removal without force, and used for nothing else. Tags have to be legible, durable, and attached by a means that can withstand at least 50 pounds of pull. ^[1]

The standard also handles the messy cases: complex equipment with multiple energy sources, shift changes (where one worker's lock has to transfer correctly before they leave), and group lockout when several people work on the same machine at once.

What is the difference between a lockout and a tagout?

A lockout uses a physical lock to hold an isolating device in the safe position. A tagout uses a warning tag with no lock. That single difference (barrier versus warning) is the most misunderstood point in LOTO training, and it's worth pinning down exactly.

With a lockout, you attach a lock to an energy-isolating device, like a breaker hasp or a valve, so the device cannot move out of the de-energized position. The lock physically stops re-energization. Only the worker who applied it holds the key.

With a tagout, you attach a standardized tag to that same device, but no lock. The tag reads something like "Do Not Operate" and names the worker. It stops nobody. It only warns.

OSHA's position is blunt: "Lockout is the preferred method of isolating machines or equipment from energy sources." ^[1] Tagout-only programs are permitted only when the isolating device physically cannot accept a lock. Even then, OSHA demands extra protective measures to reach the same level of safety a lock provides, like removing a valve handle, blocking a breaker, or opening a second disconnect.

Use a tag instead of a lock because tags are cheaper or faster, and you've got a violation. Inspectors look for exactly this.

How many injuries and deaths does LOTO prevent (and how many happen when it fails)?

OSHA estimates that compliance with 29 CFR 1910.147 prevents about 50,000 injuries and 120 fatalities a year across U.S. general industry. ^[2] Those are OSHA's own figures from the standard's regulatory analysis, not an outside estimate.

When LOTO gets skipped, the results are ugly. Caught-in or caught-between events, the category that covers most LOTO failures, accounted for 701 fatal work injuries in 2022 according to the Bureau of Labor Statistics Census of Fatal Occupational Injuries. ^[3] Amputations and crush injuries from uncontrolled energy releases rank among the worst non-fatal injuries in the BLS data.

29 CFR 1910.147 stays near the top of OSHA's most-cited list year after year. In fiscal year 2023, lockout tagout drew 2,554 federal citations, putting it among the five most-cited general industry standards. ^[4] OSHA's maximum penalty for a serious violation is $16,131 per violation as of 2024, and willful or repeated violations can reach $161,323 each. ^[5]

The pattern in OSHA investigation reports barely changes. A worker skips the procedure because the job looks quick, the machine cycles without warning, and someone loses a hand or a life. "Quick jobs" are where LOTO failures concentrate.

What energy sources does lockout tagout cover?

All of them. Most people learn LOTO around electrical hazards, but the standard is energy-agnostic. 29 CFR 1910.147 defines "energy source" as "any source of electrical, mechanical, hydraulic, pneumatic, chemical, thermal, or other energy." ^[1] Working through each type is how you build procedures that hold up.

Energy Type	Common Examples	How It's Isolated
Electrical	Motors, control panels, lighting circuits	Lockable circuit breaker, disconnect switch
Pneumatic	Air cylinders, pneumatic tools, blow-off nozzles	Valve with hasp, bleed off the line
Hydraulic	Presses, lifts, clamps	Valve, pressure bleed-off, blocking cylinders
Mechanical	Springs, gravity-loaded parts, flywheels	Block, pin, or brace to restrain movement
Thermal	Steam lines, heated platens, process fluids	Valve, cool-down wait, pipe blinds
Chemical	Process lines with reactive materials	Valve, line blinding, flushing

Gravity is the one that catches people. A raised die, ram, or press platen stores energy just by sitting up top. Break a hydraulic line or fail the blocking and it drops. Written procedures have to address gravity-loaded parts by name, usually by requiring a mechanical block or pin before anyone works underneath.

Stored electrical energy in capacitors is the other quiet hazard. Even with the breaker locked out, large capacitors in variable frequency drives can hold a lethal charge for minutes after power is cut. Procedures should call for a wait time or a live test to confirm discharge.

Who is covered by the lockout tagout standard: authorized, affected, and other employees?

29 CFR 1910.147 sorts workers into three categories, and the training differs for each.

An authorized employee is the person who actually locks out a machine to service or maintain it. This is the worker with the lock and the key. They get the deepest training: how to spot hazardous energy sources, how to isolate and verify energy control, and how to release lockout when the job ends.

An affected employee operates the machine being serviced, or works in the area where lockout is in use. They need to understand why a machine is locked and why they must never restart it or remove someone else's lock. Production workers on the same floor fall here.

Other employees are anyone else who might walk past a locked-out machine. They need enough awareness training to know what a lock or tag means and to leave it alone.

The standard is strict on one point. Only the authorized employee who applied a lock can remove it, with one narrow exception for employer-authorized removal when that employee is unavailable. An employer can remove a lock in that situation, but the standard requires a written procedure for doing so, and the absent worker must be notified before returning to work. ^[6]

For how OSHA structures training across its standards, the osha training article walks through the full framework.

What are the steps in a lockout tagout procedure?

OSHA lays out the sequence in Appendix A of 29 CFR 1910.147. It reads as the agency's model for an adequate procedure, and skipping steps is where injuries come from. Here's how it runs in practice.

1. Prepare for shutdown. Identify every energy source feeding the equipment. Know where each isolating device sits before you start. Pull the machine-specific written procedure.

2. Notify affected employees. Tell the people who operate or work around the machine that it's going down and why.

3. Shut down the equipment. Use the normal stopping procedure. Don't just yank power. Bring the machine down in a controlled way first.

4. Isolate the energy source. Move each isolating device (breaker, valve, disconnect) to the off or closed position.

5. Apply lockout or tagout devices. Each authorized employee applies a personal lock to every isolating device. Six energy sources means six lock points.

6. Release or restrain stored energy. Bleed pneumatic lines, discharge capacitors, block raised components, release spring tension. This is where most half-done procedures fail.

7. Verify isolation. Try the normal startup controls. Confirm that pressure gauges, voltage testers, and any motion read zero energy. OSHA says "verify" for a reason. You confirm. You never assume.

Releasing lockout runs the steps backward: remove tools and materials, clear all workers from the danger zone, remove locks in reverse order, notify affected employees, then restore energy.

For equipment covered by other OSHA standards, like forklifts or electrical systems, extra requirements can layer on top. The lockout tagout article covers the full written program in detail.

Does LOTO apply to construction, maritime, and agriculture, or only general industry?

29 CFR 1910.147 is a general industry standard. It does not technically reach construction (29 CFR 1926), maritime (29 CFR 1915 through 1918), or agriculture (29 CFR 1928). That's not a free pass, though.

For construction, OSHA falls back on the general duty clause (Section 5(a)(1) of the OSH Act) for energy control hazards, plus the electrical safety standards at 29 CFR 1926 Subpart K. OSHA has cited construction employers under the general duty clause for LOTO-style failures, so the missing specific standard doesn't help anyone who skips energy control.

Shipyard employment has its own lockout tagout standard at 29 CFR 1915.89, finalized in 2015. It tracks the general industry standard in most respects but adds provisions for vessels and marine work. ^[7]

For electrical work, 29 CFR 1910.333 covers electrical safety-related work practices and includes energy control requirements that overlap with 1910.147. Electrical maintenance workers need to know both, because both can apply at once.

Small manufacturers, food processors, warehouses, print shops, and any general industry employer with powered equipment sit squarely inside 1910.147. If your employees service, maintain, or clean powered equipment, the standard almost certainly applies to you.

What are the most common LOTO violations OSHA cites?

Knowing where programs break down beats memorizing a list of requirements. OSHA's citation history points to the same handful of gaps every year.

The most common one is missing or thin machine-specific procedures. An employer writes a generic lockout policy, files it in the safety binder, and calls it done. Then an inspector asks for the written procedure for a specific machine and finds nothing. 29 CFR 1910.147(c)(4) requires machine-specific procedures unless narrow equivalency conditions are met. ^[1]

Second is skipping the annual periodic inspection. It has to be documented, machine-specific, and performed by an authorized employee other than the one who normally runs that procedure. Plenty of employers never do it, or do it on paper without actually walking the procedure with workers.

Third is weak training, especially for affected employees. Authorized employees usually get trained. The production workers running nearby machines often don't.

Fourth is hardware trouble: zip ties standing in for lockout hasps, one lock covering several purposes, locks with no individual assignment.

Fifth is stretching the "minor servicing" exception too far. 29 CFR 1910.147(a)(2)(ii) exempts minor tool changes and adjustments that are routine, repetitive, and integral to production, but only when an alternative measure gives equivalent protection. Employers treat this like it covers any quick fix. It doesn't.

For how OSHA citations work and how to answer one, the incident report and osha articles are good places to start.

How do you write a lockout tagout program for a small business?

A compliant program for a small employer has four physical pieces: the written policy, machine-specific procedures, training records, and annual inspection certifications. None of it needs a consultant if you're willing to spend focused time on it.

Start with an equipment inventory. Walk every piece of powered equipment and list its energy sources. For each machine, document the location and type of every isolating device. Photograph them. The photos make training easier and the procedures far more useful.

Write the machine-specific procedures from that inventory. Each one should fit on a single laminated card that hangs on the machine or lives in a pocket. It needs the machine ID, the energy sources and their locations, the isolation steps in order, the stored-energy controls, and the verification steps. Keep it simple. A procedure nobody reads is just paper.

Run initial training for both authorized and affected employees, document it with signatures and dates, and keep those records where you can find them.

Set a calendar reminder right now for the annual procedure review. It's the most-missed requirement in OSHA audits, and it earns its keep. Machines change, procedures drift, and a fresh look catches problems before an inspector does.

If you want a structured starting point, SafetyFolio's safety program generator builds a written LOTO program with machine-specific procedure templates in about 15 minutes. That handles the documentation layer while you focus on the physical equipment inventory.

The hazard communication article pairs well with this one, because chemical energy sources in manufacturing and processing tie LOTO requirements to HazCom labeling.

What is the difference between lockout tagout and electrical safety (NFPA 70E)?

They cover related but separate situations. 29 CFR 1910.147 controls hazardous energy during servicing and maintenance. NFPA 70E covers how to protect workers who have to work on electrical equipment that stays energized. LOTO gets you to zero energy. NFPA 70E protects you when you can't get there.

29 CFR 1910.147 covers all energy types and applies whenever unexpected energization or energy release could hurt someone.

NFPA 70E, the National Fire Protection Association's "Standard for Electrical Safety in the Workplace," covers arc flash protection, approach boundaries, and PPE for energized electrical work. ^[8] It isn't an OSHA standard, but OSHA cites it as a recognized industry standard under the general duty clause.

The two overlap during electrical maintenance. De-energizing electrical equipment requires LOTO under 1910.147. If work has to proceed while equipment is live (which should be avoided whenever possible), NFPA 70E governs the protective measures.

For most small general industry employers, 29 CFR 1910.147 is the directly enforceable requirement. NFPA 70E matters most for facilities with heavy electrical infrastructure or dedicated electricians doing energized work.

PPE requirements for electrical hazards live under 29 CFR 1910.137. For how PPE layers on top of engineering controls like LOTO, the ppe section here covers it.

Does LOTO apply to cord-and-plug equipment?

Yes, with one exception. 29 CFR 1910.147(a)(2)(iii) excludes cord-and-plug connected electrical equipment from the lockout requirements, but only when the equipment is unplugged AND the plug stays under the exclusive control of the employee doing the work. ^[1]

"Exclusive control" means the plug is in that worker's hand, pocket, or line of sight, so nobody can plug it back in mid-job. Unplug a bench grinder and pocket the plug while you change the wheel, and you've met the exception. Unplug it and walk away while others are around, and you haven't.

Equipment with multiple plugs, or equipment where unplugging doesn't kill everything (some machines carry integral batteries or capacitor banks), falls outside the exception for those remaining energy sources. Those still need a full LOTO procedure.

OSHA has addressed cord-and-plug scenarios in several letters of interpretation. The message stays consistent: the exception is narrower than most people think, and when exclusive control is in any doubt, a lock is the right answer. ^[6]

Frequently asked questions

What does LOTO stand for?

LOTO stands for lockout tagout. "Lockout" means physically securing an energy-isolating device with a lock so a machine cannot be re-energized. "Tagout" means attaching a warning tag when a lock cannot be applied. OSHA's standard governing both practices is 29 CFR 1910.147, titled "The Control of Hazardous Energy (Lockout/Tagout)."

Is lockout tagout required by OSHA?

Yes. 29 CFR 1910.147 is a mandatory OSHA standard for general industry employers. It requires a written energy control program, machine-specific procedures, employee training, annual procedure inspections, and proper lockout hardware. Violations are among the most frequently cited in OSHA federal enforcement, generating over 2,500 citations in fiscal year 2023.

What is the lockout tagout standard number?

The primary OSHA standard is 29 CFR 1910.147, which covers general industry. Shipyard employment has a separate standard at 29 CFR 1915.89. Electrical safety for general industry is also addressed in 29 CFR 1910.333, which overlaps with 1910.147 for electrical energy sources.

What is the purpose of lockout tagout?

The purpose is to prevent injuries and deaths from the unexpected release of hazardous energy during machine servicing and maintenance. OSHA estimates the standard prevents about 50,000 injuries and 120 fatalities per year. The most common prevented injuries are amputations, crush injuries, and electrocutions from machines that restart unexpectedly during maintenance.

Who is required to be trained in lockout tagout?

Three groups need training under 29 CFR 1910.147. Authorized employees (workers who apply the locks) get the most thorough training. Affected employees (workers who operate nearby machines or work in the area) need enough to understand why locks are present and never to remove them. Other employees in the area need basic awareness of what locks and tags mean.

Can a supervisor remove an employee's lockout lock?

Only under narrow conditions described in 29 CFR 1910.147(e)(3). The employer must have a written procedure for employer-authorized removal. Before the lock comes off, the employer must verify the employee is not in the facility and must notify that employee before they return to work. Using this provision routinely, rather than in genuine emergencies, is a violation.

What is the difference between an authorized employee and an affected employee in LOTO?

An authorized employee performs the lockout and the service or maintenance work. An affected employee operates or uses the locked-out equipment in normal production, or works in the area where lockout is in use. Authorized employees require more detailed training. Affected employees need enough training to know they must never try to restart locked equipment.

How often does a lockout tagout program need to be reviewed?

At minimum, once per year. 29 CFR 1910.147(c)(6) requires a periodic inspection of the energy control procedures at least annually. The inspection must be certified in writing, including the date, the machines covered, the employees involved, and the name of the inspector. This is one of the most commonly missed requirements in OSHA audits of small employers.

What is the OSHA penalty for a lockout tagout violation?

As of 2024, OSHA's maximum penalty for a serious violation is $16,131 per violation. Willful or repeated violations can reach $161,323 per violation. Actual penalties vary based on gravity, employer size, history, and good faith. LOTO violations frequently receive serious classification because the injury potential from uncontrolled energy is high.

Does lockout tagout apply to small businesses?

Yes. 29 CFR 1910.147 applies to all general industry employers regardless of size as long as employees service, maintain, or clean powered equipment. OSHA scales penalties down for smaller employers (fewer than 25 employees get a 60% reduction), but the compliance requirements are identical. Small manufacturers, food processors, auto repair shops, and print shops are all covered.

What is a group lockout procedure?

A group lockout procedure applies when more than one employee works on the same equipment at the same time. Each worker must have personal protection, usually by applying a personal lock to a hasp on the isolating device, or through a group lockout box where each worker's lock secures the key to the primary lock. Every person stays protected until they remove their own lock.

Does lockout tagout cover pneumatic and hydraulic energy?

Yes. 29 CFR 1910.147 defines energy source as any source of electrical, mechanical, hydraulic, pneumatic, chemical, thermal, or other energy. Pneumatic lines must be de-pressurized and valves locked. Hydraulic systems must have pressure bled off and cylinders blocked or pinned. A machine that's electrically de-energized but still holds pressurized air is not fully locked out.

Sources

1. OSHA, 29 CFR 1910.147 The Control of Hazardous Energy (Lockout/Tagout): Full text of the OSHA lockout tagout standard including definitions, scope, written program, training, periodic inspection, and hardware requirements
2. OSHA, Control of Hazardous Energy (Lockout/Tagout) overview page: OSHA estimates the standard prevents approximately 50,000 injuries and 120 fatalities annually
3. Bureau of Labor Statistics, Census of Fatal Occupational Injuries 2022: Caught-in or caught-between injuries accounted for 701 fatal work injuries in 2022
4. OSHA, Top 10 Most Frequently Cited Standards: Lockout tagout (29 CFR 1910.147) generated 2,554 federal citations in OSHA fiscal year 2023, ranking among the top five most-cited general industry standards
5. OSHA, Penalties page: OSHA maximum penalty for a serious violation is $16,131 and for willful or repeated violations is $161,323 per violation as of 2024 adjusted penalty levels
6. OSHA, Standard Interpretations (letters of interpretation) search page: OSHA letters of interpretation addressing employer-authorized lock removal and cord-and-plug exclusive control requirements under 1910.147
7. OSHA, 29 CFR 1915.89 Control of Hazardous Energy (Lockout/Tags-Plus) for Shipyard Employment: Shipyard employment has a separate LOTO standard at 29 CFR 1915.89, finalized in 2015
8. NFPA, NFPA 70E Standard for Electrical Safety in the Workplace: NFPA 70E covers arc flash protection, approach boundaries, and PPE for energized electrical work, distinct from but overlapping with 29 CFR 1910.147
9. OSHA, 29 CFR 1910.333 Electrical Safety-Related Work Practices: 29 CFR 1910.333 addresses electrical energy control requirements that overlap with 1910.147 for electrical maintenance work
10. OSHA, 29 CFR 1910.137 Electrical Protective Equipment: 29 CFR 1910.137 sets personal protective equipment requirements for electrical hazards