A primary concern is the unexpected release of stored energy which can be mitigated through Lockout-Tagout (LOTO) procedures. This guide outlines eight critical LOTO steps to ensure personnel safety, asset health, and reliable, sustainable operations.
1. Preparation
The first step in an effective Lockout-Tagout (LOTO) procedure is preparing the equipment for shutdown. An authorized employee must locate all equipment power sources and determine how to disconnect them safely. This may involve consulting the equipment manual or contacting the manufacturer for power source information. Strict adherence to established energy control procedures is vital. These procedures are mandated by standards and regulations such as OSHA 29 CFR 1910.147, EU Directive 2009/104/EC, and NFPA 70E Electrical Safety in the Workplace Article 120.
2. Notification and shutdown
The authorized employee must notify all relevant personnel before initiating a shutdown to prevent accidental equipment energization during maintenance. Providing an estimated downtime and assuring staff of notification upon safe return to service is vital. Once communication is complete, the equipment is then shut down following the manufacturer's recommended procedure.
3. Energy source isolation
Once the equipment is powered down, the next critical step is isolating it from all energy sources - electrical, chemical, pneumatic, hydraulic, or mechanical - by physically disconnecting, removing, or blocking every potential energy source. Energy isolation may involve unplugging cords, detaching external power, closing valves, pulling fuses or flipping circuits, and employing safety devices to block moving parts.
The objective of locking out de-energized equipment is to prevent inadvertent energization and eliminate all energy hazards. Energy control procedures (ECP) for each asset must specify all isolation locations to ensure routine and reactive maintenance activities can be performed safely.
4. Applying lock and tag devices
Next, LOTO identification tags are applied to each locking device at the equipment's energy isolation points. These tags must clearly alert personnel that the equipment is locked out, including the name of the authorized employee performing service and other essential lockout information. Tags are affixed directly to the lockout device, which physically prevents equipment energization until both the device and tag are removed.
The authorized employee who applied each lockout device must maintain exclusive control of its key. All authorized employees working on the equipment must attach their individual locking device and accompanying tag to each isolation point.
5. Securing or releasing stored energy
After the tagout procedure is complete, attention turns to checking for stored energy. Even after isolation and tagging, residual energy hazards may persist within the equipment, including electric shock, air pressure, heat, motion, or gravity. Any remaining stored or hazardous energy sources must be identified, then safely disconnected, relieved, or blocked. The step is complete only when all residual energy is dissipated or rendered non-hazardous for personnel performing maintenance and repair.
6. Isolation verification
Verification of isolation ensures the equipment is fully de-energized, with all energy sources disconnected and relieved. The authorized employee must confirm that all energy hazards have been eliminated. Verification methods may include checking pressure gauges, briefly and safely attempting to start the equipment, and utilizing a multimeter to check for voltage. Only after thorough LOTO performance and verification can maintenance, repair, or upgrade safely commence.
7. Maintaining LOTO during service
Depending on the duration of servicing and maintenance activities, the work may extend across multiple shifts or days. Site-specific procedures must be established to ensure the safe continuity of the lockout process during personnel changes or when additional authorized employees join the activity. Effective communication is a vital element throughout this phase, as critical lapses can result in injuries and even loss of life.
8. Bringing equipment back online
Following servicing and maintenance activities, the equipment's safe return to service requires strict adherence to the energy restoration sequence outlined in the LOTO procedures. Essential steps include removing all tools, debris, and LOTO devices before restoring isolated energy sources. Verify the equipment's correct power connection and ensure the area is clear of personnel. Affected employees must then be notified before the equipment is safely started and returned to service. Only the authorized employee who applied the LOTO devices is authorized to remove them.
LOTO success: Beyond the procedures
Lockout-Tagout (LOTO), also known as the control of hazardous energy, is a comprehensive program reliant on the integration of documentation, procedures, periodic inspections, and continuous training. This robust approach ensures regulatory compliance and serves to:
- Safeguard personnel during critical servicing activities
- Facilitate equipment maintenance that leads to safe operational condition
- Contribute to overall equipment reliability
Beyond safety outcomes, a well-executed LOTO program reduces operational inefficiencies. Proper energization and de-energization procedures help protect equipment from damage, which can lead to costly downtime, rework, wasted materials and missed production commitments.
Despite its critical importance as a driver for safety, reliability and sustainability, Lockout-Tagout consistently ranks among the top 10 OSHA most cited standards that are not being adhered to year after year, underscoring the urgent need to understand and leverage this powerful safety program.
For more information: https://www.abb.com/global/en/areas/electrification/services/advisory-services/lock-out-tag-out
