29 CFR 1910.147: OSHA Lockout/Tagout Standard

Regulatory citation: 29 CFR 1910.147

OSHA Lockout/Tagout Standard: 29 CFR 1910.147

The Lockout/Tagout standard, found at 29 CFR 1910.147, governs the control of hazardous energy during the servicing and maintenance of machines and equipment. It requires employers to establish procedures for disabling machinery and isolating energy sources before employees perform maintenance, repair, or servicing tasks that could expose them to unexpected startup or release of stored energy.

Hazardous energy can take many forms, electrical, mechanical, hydraulic, pneumatic, chemical, thermal, or gravitational, and Lockout/Tagout (LOTO) procedures are designed to address all of them.

Why Lockout/Tagout Is Critical

Unexpected equipment startup or energy release during servicing is one of the most severe hazard categories in industrial settings, frequently resulting in amputations or fatalities. Because the consequences of LOTO failures are so severe, and because the standard's core requirements are well-established and preventable, LOTO consistently ranks among OSHA's most frequently cited standards.

Core Requirements of the Lockout/Tagout Standard

1. Written Energy Control Procedures

Employers must develop specific, documented procedures for each piece of equipment (or equipment type, where procedures are sufficiently similar) detailing the steps required to safely shut down, isolate, and lock out energy sources.

2. Employee Training

Employees must be trained according to their role: authorized employees who perform lockout procedures, affected employees who operate or work near locked-out equipment, and other employees who work in areas where LOTO procedures may be in effect.

3. Lockout Devices

Employers must provide standardized lockout devices, locks, tags, and related hardware, substantial enough to prevent removal without the use of excessive force or specialized tools.

4. Periodic Inspections

Employers must conduct periodic inspections of energy control procedures at least annually, to ensure procedures are being followed correctly and remain adequate for current equipment configurations.

The Six Basic Steps of Lockout/Tagout

1. Preparation

The authorized employee identifies all energy sources associated with the equipment and reviews the specific lockout procedure.

2. Notification

Affected employees are notified that equipment will be shut down and locked out for servicing.

3. Shutdown

The equipment is shut down using its normal operating controls.

4. Isolation

All energy-isolating devices are located and operated to disconnect the equipment from its energy sources.

5. Lockout/Tagout Application

Locks and tags are applied to each energy-isolating device, and any stored or residual energy is safely relieved, disconnected, or restrained.

6. Verification

Before work begins, the authorized employee verifies isolation is complete, often by attempting to start the equipment using normal operating controls after ensuring it's safe to do so.

Common Lockout/Tagout Compliance Mistakes

Incomplete Energy Source Identification

Complex machinery often has multiple energy sources, some obvious (electrical disconnects) and some easily overlooked (stored hydraulic pressure, spring tension, or gravitational energy from raised components).

Using Tagout Without Lockout Where Lockout Is Feasible

The standard generally requires lockout devices rather than tagout-only procedures whenever equipment is capable of being locked out, since tags alone don't physically prevent energy from being restored.

Outdated or Missing Written Procedures

As equipment is modified, replaced, or reconfigured, written LOTO procedures must be updated accordingly; outdated procedures are a common citation source.

Skipping Annual Procedure Inspections

The required annual inspection of energy control procedures is frequently overlooked, particularly in facilities without a dedicated safety compliance function.

Example: Lockout/Tagout in Practice

A maintenance technician is assigned to repair a jammed conveyor belt. Before beginning work, they follow the facility's written LOTO procedure specific to that conveyor: notifying nearby operators, shutting down the equipment using its control panel, locating and locking out the primary electrical disconnect, and relieving residual pneumatic pressure in the system per the documented procedure. Only after verifying the equipment cannot be restarted, by attempting the start button with the lock in place, does the technician begin the repair.

Frequently Asked Questions

What is the purpose of the OSHA Lockout/Tagout standard?

The OSHA Lockout/Tagout standard exists to protect employees from the unexpected startup or release of hazardous energy while servicing or maintaining machinery and equipment. Hazardous energy can take many forms beyond simple electrical power, including mechanical, hydraulic, pneumatic, chemical, thermal, and gravitational energy, all of which can cause severe injury if released unexpectedly during maintenance work. The standard requires employers to develop and follow specific, documented procedures for isolating and controlling these energy sources before any servicing begins, ensuring that equipment cannot be restarted or release stored energy while a worker is exposed to it. Because failures in hazardous energy control frequently result in amputations or fatalities, and because the standard's core requirements are well-established and largely preventable through proper procedure, Lockout/Tagout compliance is treated as a high priority by OSHA and consistently ranks among its most frequently cited standards.

Who needs Lockout/Tagout training?

OSHA's Lockout/Tagout standard defines three categories of employees, each requiring different levels of training. Authorized employees are those who actually perform lockout or tagout procedures on machines or equipment, and they require the most comprehensive training, covering energy source recognition, the specific procedures for each piece of equipment they'll service, and how to safely apply and remove lockout devices. Affected employees are those who operate or use equipment that may be locked out for servicing, or who work in an area where such servicing is performed; their training focuses on recognizing when equipment is locked out and understanding they must not attempt to restart or operate it. Other employees, meaning anyone whose job may require them to be in an area where energy control procedures are in use, receive more general awareness training about the purpose of lockout devices and the importance of not tampering with them. Employers must ensure the appropriate level of training is provided based on each employee's actual role relative to locked-out equipment.

When is lockout required instead of tagout alone?

OSHA's standard generally requires the use of lockout devices, rather than tagout devices alone, whenever a piece of equipment is designed to accept a lockout device. A lockout device physically prevents an energy-isolating mechanism from being operated, such as a padlock on an electrical disconnect switch, while a tagout device is simply a warning label indicating the equipment should not be operated, without physically preventing that from happening. Because tags alone rely entirely on the observer reading and respecting the warning, they provide a meaningfully lower level of protection than a physical lockout device. Tagout-only procedures are only permitted when equipment genuinely cannot accommodate a lockout device, and even then, the standard requires additional safety measures to compensate for the reduced protection tagout alone provides, such as extra employee training or additional means of preventing accidental energization.

How often should Lockout/Tagout procedures be reviewed or inspected?

OSHA requires employers to conduct a periodic inspection of their energy control procedures at least annually, to verify that the procedures currently in place are being followed correctly and remain adequate given any changes to equipment, processes, or facility layout since the procedures were last reviewed. This inspection must be conducted by an authorized employee who is not the one currently using the specific energy control procedure being inspected, ensuring an element of independent verification. Beyond this annual requirement, written procedures should also be updated any time equipment is modified, replaced, or reconfigured in a way that changes its energy sources or the steps needed to safely isolate them; using outdated procedures that no longer accurately reflect a machine's current configuration is a common and serious compliance gap. Employers should also review and reinforce procedures following any near-miss or incident involving hazardous energy, since these events often reveal gaps that a routine annual inspection alone may not catch.

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