Lock Out and Tag Out (LOTO)- Control of Hazardous Energy

Lock Out and Tag Out (LOTO)- Control of Hazardous Energy

In this article I will take you through the LOTO meaning …. Lock Out and Tag Out also called LOTO for short, is a critical energy control procedure which will help keep everyone safe from hazardous energy risk.

What is Hazardous Energy?

Workers servicing or maintaining machines or equipment may be exposed to serious physical harm or death if hazardous energy is not properly controlled. Craft workers, machine operators, and laborers are among the workers who face the greatest risk.

Energy sources including electrical, mechanical, hydraulic, pneumatic, chemical, thermal, or other sources in machines and equipment can be hazardous to workers. During maintenance or repair work of machines and equipment, the unexpected startup or release of stored energy can result in serious injury or death to workers.

Injuries may include electrocution, burns, crushing, cutting, lacerating, amputating, or fracturing body parts, among others.

  • A steam valve is automatically turned on, burning workers who are repairing a downstream connection in the piping.
  • A jammed conveyor system suddenly releases, crushing a worker who is trying to clear the jam.
  • Internal wiring on a piece of factory equipment electrically shorts, shocking the worker who is repairing the equipment.

LOTO Meaning and LOTO Procedures

What is LOTO? LOTO is simply Lockout Tagout. Lockout and Tagout (LOTO) is a systematic and standardized energy control procedure used to prevent the accidental startup of equipment and machinery during maintenance or repair work.

Lockout means cutting all sources of energy and installing a personal lock and tag at the source for the purpose of controlling hazardous energy (prevent the starting of this piece of machinery) while it is being cleaned, maintained, adjusted or repaired. It is the placement of a lockout device on an energy-isolating device such as a manually operated disconnect switch, a circuit breaker, a line valve or a block.

A lockout device is a mechanical means of locking that uses an individually keyed lock to secure an energy-isolating device in a position that prevents energization of a machine, equipment, or a process. (Note: push buttons, selection switches and other circuit control switches are not considered energy-isolating devices)

Tag out is a labelling process that is always used when lockout is required. The process of tagging out a system involves attaching or using an information tag that includes the following information:

  • Why the lockout/tag out is required (repair, maintenance, shutdown etc.).
  • Time and date of application of the lock/tag.
  • The name of the authorized person who attached the tag and lock to the system.

ONLY the authorized person/individual who placed the lock and tag onto the system is the one who is permitted to remove them. This procedure ensures that the system cannot be started up without the authorized individual’s knowledge


De-energization is a process that is used to disconnect and isolate a system from a source of energy to prevent the release of that energy. By de-energizing, the risk that the system could inadvertently, accidentally, or unintentionally cause harm to a person through the release of hazardous energy is eliminated.

What can be done to control hazardous energy?

Having a Lockout Tagout (LOTO) program and procedures for these scenarios will reduce the risk of injury due to the unintended or inadvertent release of hazardous energy.

A lockout program should:

  • Identify types of:
    • Hazardous energy in the workplace
    • Energy-isolating devices
    • De-energizing devices
  • Guide the selection and maintenance of protective devices, hardware, and personal protective equipment (PPE)
  • Assign duties and responsibilities
  • Describe lockout procedures for all machines, equipment, and processes
  • Determine shutdown, de-energizing, energizing, and start-up sequences
  • Describe training requirements for authorized and affected workers
  • Be audited for effectiveness

Employee Roles and Responsibilities

Each party in the workplace has a responsibility in the program. In general:

Management is responsible for:

  • Drafting, reviewing, and updating Lockout Tagout (LOTO) program and procedures.
  • Identifying the employees, machines, equipment, and processes included in the program.
  • Providing the necessary protective equipment, hardware and appliances.
  • Monitoring and measuring conformance with the program.

Supervisors are responsible for:

  • Distributing protective equipment and hardware, and ensuring its proper use by employees.
  • Making sure that equipment-specific procedures are established for the machines, equipment and processes in their area.
  • Making sure that identified employees are provided with adequate training on lockout tagout procedures.
  • Making sure that only properly trained employees perform service or maintenance that require lockout tagout.
  • Making sure that employees under their supervision follow the established lockout procedures where required.

Authorized individuals are responsible for:

  • Following the procedures that have been developed.
  • Reporting any problems associated with those procedures, the equipment, or the process of locking and tagging out.

Lockout Tagout (LOTO) procedures and work instructions

The written lockout tagout (LOTO) procedure should specify:

  • The specific machine, equipment, or process involved in the shutdown and isolation process.
  • The hazardous energy present and the type of energy-isolating or de-energizing devices required.
  • Where the lockout devices are required and how they are installed.
  • The steps for shutting down, isolating, blocking, securing, and relieving stored or residual energy.
  • The steps for placing and removing all lockout and tagout devices.
  • How the isolation can be verified.
  • How others in the area will be informed of the lockout and the return into service.

The Basic Steps of locking and tagging out a system

Lockout tagout (LOTO) procedures and program involve more than putting a lock on a switch. They are comprehensive step-by-step processes that involve communication, coordination, and training.

Affected person – persons who are not directly involved in the work requiring the hazardous energy control, but who are (or may be) located in the work area.

Competent person – a person who is qualified to engage in hazardous energy control because of knowledge, training, and experience and has been assigned to engage in such control.

1. Preparing the Equipment or Machine for shutdown

The Competent person will identify the machine, equipment, or process that requires lockout, which sources of energy (electrical, mechanical, hydraulic, chemical or a combination) are present and must be controlled, and what lockout device will be used. Further, this step involves gathering all required materials (e.g., lockout devices, tags, etc.).

2. Notify all affected personnel

The Competent person will communicate the following information to notify all affected persons.

  • What is going to be locked/tagged out.
  • Why it is going to be locked/tagged out.
  • For approximately how long the system be unavailable.
  • Who is responsible for the lockout/tag out, if not themselves.
  • Who to contact for more information.

This information should also be present on the tag required for the lockout.

3. Shutting down the Equipment or Machine

Follow shutdown procedures (either established by the manufacturer or employer). Equipment shutdown involves ensuring controls are in the off position, and verifying that all moving parts such as flywheels, gears, and spindles have come to a complete stop.

4. Isolating the System

Follow the lockout procedure for the identified machine, equipment, or process. Review the following isolation practices for various forms of hazardous energy:

  • Electrical energy – Switch electrical disconnects to the off position. Visually verify that the breaker connections are in the off position. Lock the disconnects into the off position. NOTE: Only disconnect switches or breakers that you are trained or authorized to do so, especially at high voltages.
  • Hydraulic and pneumatic potential energy – Set the valves in the closed position and lock them into place. Bleed off the energy by slowly opening the pressure relief valves. Some procedures for pneumatic energy control may require that pressure relief valves be locked in the open position. Some procedures for hydraulic energy, for example in lifting devices, may require blocking.

  • Mechanical potential energy – Some procedures for mechanical energy control require to carefully release stored energy from springs that may still be compressed.

  • Chemical energy – Locate chemical supply lines to the system and close and lockout the valves. Where possible, bleed lines and/or cap ends to remove chemicals from the system.

5. Removal of Residual or Stored Energy

Examples include:

  • Electrical energy – To find a specific method to discharge a capacitor for the system, contact the manufacturer for guidance. Many systems with electrical components, motors, or switch gears contain capacitors. Capacitors store electrical energy. In some cases, capacitors hold a charge and may release energy very rapidly. In other cases, capacitors are used to remove spikes and surges to protect other electrical components. Capacitors must be discharged in the lockout process in order to protect workers from electrical shock.

  • Hydraulic and pneumatic potential energy – Setting the valves in the closed position and locking them into place only isolates the lines from more energy entering the system. In most cases, there will still be residual or stored energy left in the lines as pressurized air or fluid. This residual energy can be removed by bleeding the lines through pressure relief valves. Verify depressurization or use flange-breaking techniques. Contact the manufacturer for more specific details, or if no pressure relief valves are available, what other methods are available.

  • Chemical energy – If available, bleed lines and/or cap ends to remove chemicals from the system.

6. Perform Lockout Tagout

When the system’s energy sources are locked out, there are specific guidelines that must be followed to make sure that the lock cannot be removed, and the system cannot be inadvertently operated. These guidelines include:

  • Each lock should only have one key (no master keys are allowed).
  • All keys must be removed from locks and kept with the person who applied the lock.
  • There should be as many locks on the system as there are people working on it. For example, if a maintenance job requires 3 workers, then 3 locks should be present – each of the individuals must place their OWN lock on the system. Locks can only be removed by those who installed them and should only be removed using a specific process

7. Verify isolation of Equipment or Machine

Verify that the system is properly locked out before beginning any work. Verification can take place in several ways:

  • The machine, equipment, or process controls (push buttons, switches, etc.) are engaged or activated and the result is observed. No response means isolation is verified. Return controls to the safe position (off).
  • Visual inspection of:
    • Electrical connections to make sure they are open.
    • Suspended parts are lowered to a resting position or blocked to prevent movement.
    • Other devices that restrain machine or process movement.
    • Valve positioning for double block and bleed (for pipes or ducts) – closing two valves of a section of a line, and then bleeding (or venting) the section of the line between the two closed valves.
    • Presence of solid plate used to absolutely close a line – called line blanking (for pipes or ducts).
    • Any other acceptable method of energy isolation.
  • Testing of the equipment:
    • Test circuitry (should be done by a certified electrician) – Note: equipment with capacitors needs to be cycled until all energy is drained.
    • Check pressure gauges to make sure hydraulic and pneumatic potential energy has been removed.
    • Check temperature gauges to make sure thermal energy has been discharged.

Choose the method that will make sure that the energy to the system has been isolated without creating other hazards during the verification.

8. Perform Maintenance Activities

Complete the activity that required the system to be locked out.

9. Remove Lockout Tagout Devices

To remove locks and tags from a system that is now ready to be put back into service, the following general procedure can be used:

  • Inspect the work area to make sure all tools and items have been removed.
  • Confirm that all employees and persons are safely located away from hazardous areas.
  • Verify that controls are in a neutral position.
  • Remove devices in the opposite order in which they were installed and re-energize the system.
  • Notify affected employees that servicing is completed.


In today’s rapidly evolving industrial landscape, workplace safety remains a paramount concern for both employers and employees. As industries continue to embrace technological advancements, the potential hazards and risks associated with machinery and equipment operation also increase. One crucial aspect of ensuring workplace safety is the proper implementation of a lockout tagout program.

Lockout Tagout is not just placing a lock and tag, it is both a moral and legal obligation that primarily protects workers from the unexpected release of hazardous energy resulting in serious injury or death, it also preserves the equipment as well as protects employers from direct and indirect costs resulting from accidents.

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