29 CFR 1910.147: OSHA's Control of Hazardous Energy (Lockout/Tagout) Standard

OSHA 29 CFR 1910.147 hazardous energy control standard featuring industrial lockout/tagout devices, energy isolation, and LOTO procedures.

29 CFR 1910.147 is OSHA’s general industry standard titled “The Control of Hazardous Energy (Lockout/Tagout).” It establishes minimum performance requirements for the control of hazardous energy during the servicing and maintenance of machines and equipment where the unexpected energization, startup, or release of stored energy could cause injury to employees.

This article is a regulatory interpretation guide — it addresses what the standard requires, when it applies, its scope boundaries, and how it intersects with electrical-specific OSHA standards. It is a companion to, not a replacement for, the Complete Guide to Lockout/Tagout for Electrical Systems. It is part of the Industry Standards & Regulations Resource Center.

Important framing: This article describes regulatory requirements based on current OSHA regulatory text. It does not constitute legal advice or an employer-specific compliance determination. Employers should consult qualified legal and safety professionals and the current regulatory text when evaluating their specific obligations.

What 29 CFR 1910.147 Is

1910.147 is a performance-based standard — it establishes minimum outcomes that an energy control program must achieve. It does not prescribe a single universal lockout/tagout procedure. Employers are required to develop procedures suited to their machines, equipment, and operations that meet the standard’s requirements.

The standard’s purpose, stated in 1910.147(a)(1), is to prevent injury from unexpected energization, startup, or release of stored energy during servicing and maintenance. The word “unexpected” is significant: the concern is not with intentional energization during normal production, but with energy that presents hazard because the servicing employee is exposed to it while the machine or equipment is not in its normal operating state.

Hazardous Energy Beyond Electricity

A common misconception is that 1910.147 concerns only electrical energy. OSHA’s definition of “hazardous energy” under 1910.147(b) encompasses:

  • Electrical energy
  • Mechanical energy (stored in springs, suspended parts, or rotating components)
  • Hydraulic energy
  • Pneumatic energy
  • Chemical energy
  • Thermal energy
  • Other forms of stored or residual energy

This breadth is intentional. A machine may be electrically de-energized while remaining hazardous from a pressurized hydraulic system, a compressed spring, a suspended load, or retained thermal energy. Effective hazardous energy control requires identifying and addressing all energy sources on the machine or equipment — not only electrical isolation.

When 1910.147 Applies

The standard applies to the servicing and maintenance of machines and equipment. OSHA defines “servicing and/or maintenance” in 1910.147(b) to include activities such as constructing, installing, setting up, adjusting, inspecting, modifying, and maintaining and/or servicing machines or equipment — including lubrication, cleaning, unjamming, and making adjustments or tool changes, where the employee may be exposed to the unexpected energization, startup, or release of hazardous energy.

Normal production operations are generally outside the standard’s scope. When an employee performs servicing or maintenance activities during normal production — as part of or adjacent to the production process — the standard applies if the employee could be exposed to unexpected energization, startup, or stored-energy release. Whether an activity constitutes covered servicing during production is a factual determination based on the specific activity, the exposure, and the applicable exceptions.

Exceptions and Scope Boundaries

1910.147(a)(1)(ii) explicitly states the standard does not apply to:

  • Construction, agriculture, and shipyard employment (Parts 1915, 1917, 1918)
  • Installations under the exclusive control of electric utilities for the purpose of power generation, transmission, and distribution, including related equipment for communication or metering
  • Exposure to electrical hazards from work on, near, or with conductors or equipment in electric utilization installations covered by Subpart S of Part 1910 — this is the critical electrical boundary discussed further below
  • Oil and gas well drilling and servicing

These exclusions mean 1910.147 is not “the OSHA electrical LOTO standard” as a universal description. Its electrical-hazard exclusion for Subpart S work means electrical LOTO for electrical utilization work in general industry is primarily governed by 1910.333 (under Subpart S), not 1910.147. This boundary is addressed specifically in the section on 1910.147 vs. 1910.333 below.

Minor Servicing Exception

Under 1910.147(a)(2)(ii), the standard does not apply to minor tool changes and adjustments and other minor servicing activities that take place during normal production operations if the activity is routine, repetitive, and integral to the use of the production equipment — and if the work is performed using alternative measures that provide effective protection.

This exception is narrow and all conditions must be met. “Quick” or “simple” work does not automatically qualify. OSHA evaluates whether the activity is truly routine and repetitive as part of the production process, whether effective alternative protection is actually in place, and whether the employee is exposed to hazardous energy during the activity. Employers relying on this exception should document the basis for applying it to specific activities.

Cord-and-Plug Exception

Under 1910.147(a)(2)(iii), the standard does not apply to work on cord-and-plug-connected electrical equipment when the equipment is unplugged from the energy source and the plug is under the exclusive control of the employee performing the servicing or maintenance. Both conditions are required. If the plug is not under exclusive employee control — because it is accessible to others, or because multiple employees are working on the equipment — this exception does not apply. Unplugging alone, without exclusive plug control, does not satisfy the standard’s requirements.

Required Energy Control Program

1910.147(c) requires employers to establish an energy control program consisting of three integrated elements:

  • Energy-control procedures — documented procedures for the control of hazardous energy
  • Employee training — training appropriate to each employee’s role
  • Periodic inspections — at least annual inspection of each energy-control procedure

These three elements are not independent choices. An employer that has written procedures but has not trained employees, or that trains employees but does not inspect procedures periodically, has not established a compliant energy control program under 1910.147(c).

Energy-Control Procedures

1910.147(c)(4) requires employers to develop, document, and utilize energy-control procedures for the control of potentially hazardous energy when employees are engaged in covered activities.

Documentation Requirement and Exception

Procedures must be documented. OSHA provides a limited exception from the documentation requirement under 1910.147(c)(4)(i) when all of the following conditions exist: the machine or equipment has no potential for stored or residual energy or reaccumulation of stored energy after shutdown; the machine or equipment has a single energy source that can be readily identified and isolated; the isolation and locking out of the energy source will completely de-energize and deactivate the machine or equipment; the machine or equipment is isolated from the energy source and locked out during servicing or maintenance; a single lockout device will achieve a locked-out condition; the lockout device is under the exclusive control of the authorized employee; the servicing or maintenance does not create hazards for other employees; and the employer has had no accidents involving unexpected activation or reenergization of the machine or equipment during servicing or maintenance. All eight conditions must be satisfied. Most industrial equipment does not meet all of them.

Required Procedure Content

Under 1910.147(c)(4)(ii), each procedure must include: the intended use of the procedure; steps for shutting down, isolating, blocking, and securing the machine or equipment; steps for the placement, removal, and transfer of lockout or tagout devices and the responsibility for them; and requirements for testing the machine or equipment to determine and verify the effectiveness of lockout devices, tagout devices, and other energy-control measures.

Lockout vs. Tagout

The distinction between lockout and tagout is one of the most frequently misunderstood aspects of 1910.147. They are not equivalent options that employers may choose between freely.

Under 1910.147(c)(1), lockout is the preferred method when an energy-isolating device is capable of being locked out. When such a device is lockable, the employer’s energy control program must use lockout — unless the employer can demonstrate that the tagout program will provide full employee protection equivalent to that provided through a lockout program.

The demonstration of equivalent protection for tagout is not a simple assertion. OSHA expects employers to show that additional measures are in place to provide the equivalent level of protection. Additional measures described by OSHA include removing an isolating circuit element, blocking a controlling switch, opening an extra disconnecting device, or removing a valve handle to reduce the likelihood of inadvertent energization.

When the energy-isolating device is not capable of being locked out, a tagout device may be used — again subject to additional protective measures and the full requirements of 1910.147.

A tag alone is not a lock. A tagout device provides a warning — it does not physically prevent energization. OSHA is explicit that tagout provides less protection than lockout. Tagout systems are appropriate when lockout is genuinely not achievable, not as a convenience substitution for lockout where lockout is feasible. Employers who use tagout must ensure that employees understand this distinction and that the additional protective measures are consistently applied.

Authorized, Affected, and Other Employees

1910.147 establishes distinct roles with distinct training requirements.

Authorized employees are those who lock out or tag out machines or equipment to perform servicing or maintenance. These are the employees who apply and remove energy-control devices. The term is not limited to electricians — any employee who performs covered servicing or maintenance and applies lockout/tagout devices must be trained as an authorized employee.

Affected employees are those whose job requires them to operate or use machines or equipment on which servicing or maintenance is being performed under lockout or tagout, or whose job requires them to work in an area where such servicing is performed. Affected employees do not apply or remove lockout/tagout devices but must be trained to understand the purpose of the energy control program and why they must not restart or reenergize equipment.

Other employees are those who work in areas where energy control procedures are used. They must be instructed about the prohibition on restarting or reenergizing machines or equipment that are locked out or tagged out.

These are not merely administrative labels. The training content required differs by role, and the failure to train employees in their applicable role is a 1910.147 violation.

Training and Retraining

Under 1910.147(c)(7), the employer must provide training to ensure that the purpose and function of the energy control program are understood by employees and that the knowledge and skills required for the safe application, use, and removal of energy controls are acquired. Training content differs by employee role as described above.

Retraining is required when: there is reason to believe an employee does not have the required knowledge or skills; there is a change in job assignments, machines, equipment, or processes that present a new hazard; or there is a change in energy control procedures. The standard does not require retraining on a fixed calendar cycle absent one of these triggering conditions — though employers may establish more frequent training as a matter of program policy.

Periodic Inspections

Under 1910.147(c)(6), the employer must conduct a periodic inspection of the energy control procedure at least annually. The purpose of this inspection is to ensure that the procedure continues to be implemented properly and that the employees are familiar with their responsibilities.

This is a procedure inspection — it involves reviewing the written procedure and verifying that the employees who use it are implementing it correctly. It is not merely an inspection of padlocks or hardware. OSHA requires that the inspection be performed by an authorized employee other than the one(s) using the procedure.

The standard also requires that the employer certify that the inspection has been performed. The certification must identify the machine or equipment on which the procedure was used, the date of the inspection, the employees included in the inspection, and the name of the inspector. For tagout procedures, the employer must also review each authorized employee’s responsibilities under the energy-control procedure with that employee as part of the inspection.

Applying and Releasing Lockout/Tagout

1910.147(d) establishes the sequence of steps for applying energy controls, and 1910.147(e) addresses the steps for release from lockout or tagout. The standard establishes required elements — it does not prescribe a single universal step count, as the appropriate sequence depends on the specific equipment and energy sources involved.

Applying Energy Controls

Required elements include: notifying affected employees that lockout or tagout will be used and the reason; identifying all energy sources associated with the machine or equipment; shutting down the machine or equipment using the established procedure; operating all energy-isolating devices to isolate the machine from its energy sources; applying lockout or tagout devices to each energy-isolating device; controlling all stored or residual energy (see Stored and Residual Energy below); and verifying isolation and de-energization before beginning work.

Releasing from Lockout/Tagout

Before restoring energy, the employer must ensure: that the machine or equipment components are operationally intact; that all employees are safely positioned or removed from the machine or equipment area; that all tools and other items are removed; and that affected employees are notified that the lockout or tagout devices are about to be removed and the machine reenergized.

Device Removal

The lockout or tagout device must be removed by the employee who applied it. This is the baseline rule. OSHA permits employer-directed removal — removal of a device by someone other than the employee who applied it — only when that employee is not available and the employer’s procedure addresses the specific steps required: verifying that the employee is not at the facility, making all reasonable efforts to contact the employee to inform them of the removal, and ensuring the employee has knowledge of the removal before they resume work. This exception requires a documented procedure and genuine due diligence. It does not mean a supervisor may remove another employee’s lock as a matter of convenience.

Stored and Residual Energy

After isolation and lockout/tagout application, all stored or residual energy must be relieved, disconnected, restrained, or otherwise rendered safe. This requirement — under 1910.147(d)(5) — is one of the most operationally significant aspects of the standard and one of the most commonly incomplete in practice.

Stored and residual energy can include: capacitor charge in electrical systems; compressed springs or spring-loaded components; pressurized hydraulic or pneumatic systems; suspended loads or parts held by gravity; thermal energy in heated processes or components; and chemical energy in retained process materials.

If there is a possibility of reaccumulation of stored energy to hazardous levels, verification of isolation must continue until the servicing and maintenance is complete or until the possibility of such accumulation no longer exists. This is not a one-time check at the beginning of the job.

Contractors and Outside Personnel

Under 1910.147(f)(2), when outside servicing personnel (contractors) are engaged in activities covered by 1910.147, the on-site employer and the outside employer must inform each other of their respective lockout or tagout procedures. Each employer must ensure that their employees understand and comply with the restrictions and prohibitions of the other employer’s energy control program. This is a bilateral obligation — it is not satisfied by one employer simply handing the other a procedure document without ensuring employee understanding.

For the broader framework of how multiple employers coordinate safety responsibilities on a shared worksite, employers should also consult OSHA’s multi-employer worksite guidance and applicable requirements under their specific industry standards.

Group Lockout/Tagout

Under 1910.147(f)(3), when servicing or maintenance is performed by a crew, craft, department, or other group, they must utilize a procedure that affords the employees a level of protection equivalent to that provided by a personal lockout or tagout device.

Group lockout procedures must address: primary responsibility for a set number of employees working under the protection of a group lockout or tagout device; provision for each authorized employee to affix a personal lockout or tagout device to the group lockout device (such as a group lockout hasp) when they begin work and to remove their device when they stop working on the machine or equipment; and coordination with authorized employees who are working simultaneously on the same machine or equipment.

The requirement for individual device affixation under group procedures is significant: one group lock on a hasp, applied by one employee, does not provide individual accountability for all members of a crew. Each authorized employee working under group LOTO must have their own device on the hasp so that the machine cannot be reenergized while any one of them is still exposed. Group LOTO does not reduce individual accountability — it structures it for a multi-employee context.

Shift and Personnel Changes

Under 1910.147(f)(4), specific procedures must be used during shift or personnel changes to ensure the continuity of lockout or tagout protection, including provisions for the orderly transfer of lockout or tagout device protection between off-going and on-coming employees to minimize exposure to hazards from unexpected energization, startup, or release of stored energy.

OSHA does not mandate a single transfer method. Employers may use a variety of approaches — including sequential lock exchange between outgoing and incoming authorized employees, continued use of a group hasp with individual device transfer, or other methods — as long as the procedure ensures that protection is continuous and that no authorized employee is left unprotected during the transition. The key requirement is an orderly, documented transfer that prevents any gap in protection between shifts.

1910.147 vs. 1910.333 / Subpart S

The boundary between 1910.147 and 1910.333 (under Subpart S) is one of the most practically important and frequently misunderstood aspects of OSHA’s hazardous energy control framework for electrical workers.

1910.147 excludes from its scope electrical hazard exposures from work on, near, or with conductors or equipment in electric utilization installations covered by Subpart S of 29 CFR Part 1910. This means that when an employee’s exposure to hazardous energy arises from electrical work covered by Subpart S — such as working on, near, or with electrical utilization conductors or equipment — 1910.333 and Subpart S, not 1910.147, govern the energy control requirements for that electrical hazard.

1910.333 (Selection and use of work practices) establishes OSHA’s electrical safety work-practice requirements for general industry, including requirements for establishing an electrically safe work condition (de-energization, isolation, lockout/tagging, and verification) for electrical work. See OSHA Electrical Safety Requirements: 29 CFR 1910 Subpart S.

Both standards may apply simultaneously when a machine involves both electrical and non-electrical energy sources. In that case, the electrical energy hazards are governed by Subpart S / 1910.333, and the non-electrical hazardous energy sources (hydraulic, pneumatic, mechanical, thermal) are governed by 1910.147. The employer’s energy control program must address both.

OSHA issued an interpretation letter on November 24, 2025, addressing the relationship between 1910.147 and 1910.333. Interpretation letters explain OSHA’s understanding of existing requirements — they do not create new regulatory obligations. Employers seeking current OSHA guidance on specific 1910.147/1910.333 boundary questions should consult the OSHA interpretation letters index for the current text of that letter.

For the broader electrical safety regulatory framework, see OSHA Requirements for Electrical Safety in the Workplace.

Utility Work and 1910.269

29 CFR 1910.269 is OSHA’s standard for electric power generation, transmission, and distribution. It applies to work by electric utilities and related employers on generation, transmission, and distribution installations, and it contains its own energy control requirements that differ from 1910.147 in significant respects.

1910.147 explicitly excludes from its scope installations under the exclusive control of electric utilities for generation, transmission, and distribution. Work within the scope of 1910.269 is governed by that standard’s specific energy control requirements — not by 1910.147. Employers engaged in utility-side work should apply 1910.269’s requirements and consult qualified legal and safety professionals regarding which standard governs specific operations.

Common Compliance Misunderstandings

Several persistent misunderstandings about 1910.147 affect how employers and employees implement the standard in practice.

“1910.147 only covers electrical energy.” False. The standard covers all forms of hazardous energy — electrical, mechanical, hydraulic, pneumatic, chemical, thermal, and stored/residual. Effective compliance requires identifying and controlling all energy sources.

“Turning equipment off equals isolation.” Not necessarily. Shutting down a machine is a step in the energy control sequence, but it is not isolation. Isolation requires operating energy-isolating devices — disconnects, valves, and other devices that physically prevent energy from reaching the machine — and then applying lockout/tagout devices to those isolating devices.

“A tag is equivalent to a lock.” Not under 1910.147. Lockout is the preferred method when lockout is feasible. Tagout provides a warning only — it does not physically prevent energization. Additional protective measures are required when tagout is used, and tagout may be used in place of lockout only when the employer can demonstrate that tagout provides equivalent protection.

“Unplugging always satisfies LOTO.” Only where both conditions of the cord-and-plug exception are fully met: the equipment is unplugged and the plug remains under the exclusive control of the servicing employee. A plug accessible to others, or work involving multiple employees, does not meet the exception.

“Annual inspection means checking padlocks.” The periodic inspection under 1910.147(c)(6) is a procedure inspection — a review of the written energy-control procedure and a verification that employees are implementing it correctly. It requires review with participating employees and a written certification.

“Only electricians can be authorized employees.” False. Any employee who performs covered servicing or maintenance and applies lockout/tagout devices must be trained as an authorized employee, regardless of their trade or craft.

“Supervisors can remove another employee’s lock.” Only through the employer-directed removal procedure under 1910.147(e)(3), which requires specific documented steps including verifying the employee is not at the facility, making all reasonable contact efforts, and ensuring the employee is informed before returning to work. It is not a general supervisory prerogative.

“One group lock eliminates individual accountability.” Under 1910.147(f)(3), each authorized employee working under group LOTO must affix their own personal device to the group lockout hasp. One lock by one employee does not protect other crew members who are still exposed.

“Quick work automatically qualifies as minor servicing.” The minor-servicing exception requires the activity to be routine, repetitive, and integral to the use of the production equipment — and alternative measures providing effective protection must be in place. Duration alone does not qualify an activity for the exception.

“1910.147 covers all electrical work.” It does not. Work on, near, or with conductors or equipment in electric utilization installations covered by Subpart S is excluded from 1910.147’s scope. For that work, 1910.333 and Subpart S apply.

Practical Takeaway

29 CFR 1910.147 establishes a performance-based framework for controlling hazardous energy during servicing and maintenance. Its requirements — an energy control program, documented procedures, training, and periodic inspection — are interconnected. A program that has procedures but lacks training, or that has training but skips periodic inspection, is incomplete under the standard.

The standard’s scope is broader than electricity and narrower than all electrical work. It covers all forms of hazardous energy during covered servicing and maintenance, but it expressly excludes electrical utilization work covered by Subpart S, utility generation/transmission/distribution work, and the specific activities addressed by its exceptions — each of which has defined conditions that must be fully met before the exception applies.

Lockout/tagout is one essential element of electrical and industrial safety. It does not independently resolve shock hazards from live electrical work, arc flash risk, or hazards that require arc-rated PPE, qualified-person protections, and safe work methods under NFPA 70E and applicable OSHA standards. See the Complete Guide to NFPA 70E, the Complete Guide to Energized Electrical Work, and the Complete Guide to Electrical PPE for the broader framework.

Related Resources

Recommended Products

This article addresses regulatory requirements for hazardous energy control. Insulated hand tools are relevant where electrical work remains necessary on energized systems after all LOTO and de-energization obligations have been evaluated and addressed. They do not satisfy 1910.147’s energy-isolation and lockout requirements and must never be used as a substitute for establishing an electrically safe work condition where one is required.

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Safety Notice

The information in this article is for general educational purposes. It does not constitute legal advice, compliance determinations, or regulatory guidance specific to any employer, facility, or jurisdiction. OSHA requirements may change; always consult the current regulatory text, applicable OSHA standards, and qualified legal and safety professionals when evaluating specific obligations. Lockout/tagout is one element of an electrical and industrial safety program — it does not independently address arc flash, shock hazards from energized electrical work, or other hazards requiring additional controls, qualified personnel, and appropriate PPE.