Lockout/Tagout

OSHA's Control of Hazardous Energy standard (29 CFR 1910.147) establishes comprehensive requirements for lockout/tagout programs. Understanding these requirements enables organizations to develop compliant programs that protect workers from hazardous energy.

Scope and Application defines which activities require LOTO procedures. The standard applies to servicing and maintenance activities where unexpected energization or startup could cause injury. Normal production operations are excluded unless workers must remove or bypass guards or place body parts in danger zones.

Energy Control Procedures must be developed for each machine or equipment with hazardous energy. Procedures must specify the scope, purpose, and authorization; steps for shutting down, isolating, blocking, and securing equipment; steps for placement and removal of devices; and requirements for testing to verify effectiveness.

Lockout Devices must be standardized within facilities by color, shape, or size. Each device must be durable enough to withstand the environment, standardized for identification, substantial enough to prevent removal without excessive force, and identifiable to indicate who applied the device.

Tagout Requirements apply when lockout is not possible. Tags must warn against hazardous conditions and include the identity of who attached them. Tagout alone requires additional safety measures because tags don't physically prevent equipment operation.

Training Requirements mandate that authorized employees understand energy sources, types and magnitude of energy, and methods for isolation and control. Affected employees must know the purpose and use of LOTO procedures. Other employees must know that they cannot attempt to start or use equipment that is locked out.

Periodic Inspection requires annual certification that procedures are being followed properly. Inspections must be conducted by authorized employees other than those using the procedure being inspected. Documentation of inspections must be maintained.

Group Lockout procedures address situations where multiple employees perform servicing on equipment. Procedures must ensure that each authorized employee is protected from hazardous energy to the same degree as individually applied locks.

Comprehensive energy source identification forms the foundation of effective LOTO programs. Every potential energy source that could harm workers must be identified and addressed in equipment-specific procedures.

Electrical Energy presents obvious hazards from shock and arc flash. Control involves disconnecting at appropriate points, verifying de-energization, and applying ground connections where appropriate. Stored electrical energy in capacitors must be discharged before work begins.

Mechanical Energy includes energy stored in springs, rotating flywheels, and moving components. Control may involve blocking, chaining, or physically restraining components that could move. Verification includes confirming that motion has stopped and cannot restart.

Hydraulic Energy in pressurized systems can cause injection injuries or sudden movement of actuators. Control involves relieving pressure, blocking cylinders, and disconnecting power units. Stored pressure in accumulators requires specific attention.

Pneumatic Energy presents similar hazards to hydraulic systems. Control involves relieving pressure, blocking components, and bleeding air from systems. The compressibility of air requires verification that pressure has been completely relieved.

Thermal Energy from hot or cold surfaces can cause burns or tissue damage. Control may involve allowing equipment to reach safe temperatures before work begins. Hot work permits and thermal PPE provide additional protection.

Chemical Energy includes hazardous materials in process equipment. Control involves draining, purging, and ventilating to remove hazardous substances. Monitoring may be required to verify safe conditions.

Gravitational Energy in raised components or suspended loads presents crushing hazards. Control involves lowering components to rest or blocking them in position. Safety blocks and chains prevent movement during work.

Energy Source Survey documents all energy sources for each piece of equipment. This survey provides the foundation for developing equipment-specific LOTO procedures that address all hazards workers may encounter.

Effective LOTO implementation requires systematic approaches to procedure development, device deployment, and training that ensure consistent protection across all maintenance activities.

Procedure Development begins with energy source surveys for each piece of equipment. Procedures must be specific enough to provide clear guidance while practical enough for actual use. Involvement of maintenance personnel in procedure development ensures practicality and builds ownership.

Equipment Identification uses labels, tags, or color coding to identify energy isolation points. Clear identification enables workers to locate correct isolation points without confusion. Standardized labeling systems support consistent application across facilities.

Device Selection matches lockout devices to isolation point characteristics. Locks must fit the devices being controlled, and multiple lock hasps enable group lockout. Standardization within facilities enables workers to recognize proper devices.

Verification Procedures confirm that energy isolation is effective before work begins. Verification involves attempting to restart equipment through normal controls and testing for presence of residual energy. Verification is essential because isolation point errors or stored energy could leave equipment energized.

Work Execution proceeds only after isolation and verification are complete. Workers must maintain awareness that LOTO devices are in place and must not bypass or remove others' devices. Any changes to work scope require reassessment of energy control needs.

Removal Procedures ensure safe device removal after work completion. The employee who applied devices should remove them. Pre-removal verification confirms that tools are removed, guards are reinstalled, and workers are clear of danger zones.

Documentation provides records of procedure execution, periodic inspections, and training completion. Documentation demonstrates compliance during regulatory inspections and supports continuous improvement of LOTO programs.

Various special situations require adaptation of standard LOTO approaches while maintaining worker protection. Understanding these situations enables practitioners to develop appropriate procedures for all maintenance scenarios.

Group Lockout protects multiple workers simultaneously servicing equipment. Approaches include group lockbox systems where each worker applies their lock to a box containing the single key for the primary lock. Other approaches use multiple-lock hasps that each worker locks. Each approach ensures no worker can be endangered by another removing protection.

Shift Turnover requires procedures for transferring LOTO protection between shifts without leaving workers unprotected. Overlap periods, documented transfer procedures, and clear communication ensure continuous protection across shift changes.

Contractor Activities present coordination challenges when outside contractors perform maintenance. Host employers must communicate LOTO requirements and coordinate procedures. Contractors must follow host procedures or have their own procedures reviewed and approved.

Complex Equipment with multiple energy sources or extensive isolation requirements may need detailed written procedures that workers follow step-by-step. Checklists ensure no isolation points are missed on equipment with many energy sources.

Limited Lockout Capability exists where isolation devices cannot accept locks due to equipment design. In these situations, tagout alone may be used with enhanced protection measures including constant presence of authorized employees, greater use of PPE, and heightened awareness procedures.

Minor Servicing Exception may apply to routine, repetitive activities during normal production if alternative protective measures provide effective protection. Strict criteria govern this exception, and it should not be applied broadly.

Hot Work situations where equipment cannot be fully de-energized require special procedures that protect workers from residual hazards. Enhanced PPE, barriers, and buddy systems provide protection when complete isolation is not possible.