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Updated: Jun 8, 2022

Purpose of Lock-out / Tag-out Practice

Lock-Out / Tag-Out (LOTO) refers to the specific practices and guidelines to safeguard employees from the unexpected start-up, movement, activation, energizing, the release of energy, etc of machinery, equipment, plant, systems during service, maintenance or inspection activities.

Lock out - Tag out practice and Seven steps that save lives (photo credit:

In short: To protect people involved in a certain job from getting hurt by the system they work on.

Lockout tag out is a procedure which can be part of a safety procedure. See the second step of seven steps for safety – Disconnect and secure against reconnection or Jan De Nul High Voltage Access procedure step 5 (Take measures against starting up).

Lock-Out / Tag-Out is the safety procedure where the work area is marked properly and secured against the power reconnection with locks. The purpose of this is to prevent injury due to unexpected energizing or start-up of machines and equipment, or the release of stored energy.

Field of Application

  1. Shutting down (part) of machinery, equipment, and systems.

  2. An employee is required to remove or bypass machine guards or other safety devices.

  3. An employee is required to place any part of his or her body into a point of operation or into an area on a machine or piece of equipment where work is performed, or into the danger zone associated with the machine’s operation.

  4. Servicing and or maintaining of machines or equipment when the source of energy is electrical, mechanical, hydraulic, chemical, thermal, or otherwise energized.

  5. Constructing, installing, setting up, adjusting, inspecting, modifying, maintaining, including lubrication, cleaning or unjamming of machines or equipment, and making adjustments or tool changes where employees could be exposed to the unexpected energization of the equipment or release of hazardous energy.

When is a Lock-Out / Tag-Out procedure not needed

  1. Servicing and or maintenance of equipment performed during normal production operations if safeguarding provisions are effective in preventing worker exposure to hazards created by the unexpected energization or start-up of machines or equipment, or the release of Energy.

Lockout tagout safety

2. Minor tool changes and adjustments.

3. Minor servicing activities that take place during normal operations which are routine repetitive, and integral to the use of that equipment, as long as workers are effectively protected by alternative measures which provide effective machine safeguarding protection.

4. Work on cord and plug connected equipment, if: The equipment is unplugged from the energy source and the authorized employee has exclusive control of the plug.


  • Tag do not provide physical restraint.

  • Tags should not be removed without authorization and are never to be bypassed, ignored or defeated.

  • Tags are essentially warning devices affixed to energy isolating devices and do not provide the physical restraint on those devices that is provided by a lock.

  • Tags must be legible and understandable by all employees.

Danger! Do not operate safety tag
  • Tags and their means of attachment must be made of materials which will withstand the environmental conditions encountered in the workspace.

  • Tags must be securely attached so that they cannot inadvertently or accidentally be detached during use.

  • Locks must be substantial enough to prevent removal without the use of excessive force or unusual techniques such as the use of bolt cutters or other metal cutting tools.

  • If it is not possible to use lock-out devices, tags are located where the lock is supposed to be.

!!! Care must be taken that the tag out will provide protection at least as effective as a lock and will assure full personnel protection.
  • The tag out can be made as effective as a lock when a circuit element is removed and isolated, a controlling switch is blocked, an extra disconnecting device is opened, or a valve handle is removed to reduce the potential for inadvertent energization while the tags are attached.

Seven Steps That Save Lives

As an example of safety procedures, we will discuss the safe working procedures used by HV field technicians these procedures are known under the name Seven steps that save lives. These steps are in line with common standards for safe working procedures. It is recommended to do risk assessment throughout the work.

The step order can vary according to the procedure used (for example issuing permit to work):

  1. Identification of the work location

  2. Disconnection and securing against reconnection

  3. Protection against any other live parts

  4. Special precautions close to bare conductors

  5. Proving the installation dead

  6. Carrying out earthing and short-circuiting

  7. Issuing a permit to work

1. Identification of the work location

Identify the right work location and mark it clearly. The work location should have appropriate access and lighting. Non-authorized persons shall be restricted from entering the work location.

Lockout Tagout identification

2. Disconnect and secure against reconnection

Disconnect all possible points of power supply. Secure the reconnection by means of a lockout and tag out the procedure to ensure that electrical equipment does not accidentally come alive. Take special care with transformers of which the secondary may be alive.

3. Protection against any other live parts

Put formal warning notices on panels or cabins you are not working on. Additional physical barriers must be applied (locks etc.) when live equipment is exposed. Recheck that you have the correct point of work.

!!! When multiple cabinets are open you might by accident start working on the wrong cabinet.

4. Special precautions when close to bare conductors

There might arise a situation where you are working near potentially live parts, or there might be a situation where you can accidentally touch live parts when putting safety barriers.

!!! Take special precautions (insulation gloves and or safety mats), especially if you are within a meter of a live connection. Take very special care on a moving vessel as the ship may suddenly start rolling, so never use a safety stool as is a standard practice ashore.

5. Proving the installation is dead

The installation needs to be checked with appropriate testing gear. Test the instrument for proper functioning first. Then verify with the test instrument that the installation is dead. Recheck the test instrument, only then you are sure your installation is dead.

6. Carrying out earthing and short-circuiting

Earthing makes the installation free of residual charges and short-circuits the system in case of a fault current. Use only equipment designed for this purpose.


Reference: High Voltage Safety by ANTWERP MARITIME ACADEMY

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