1.1.16 Lockout systems

“Lock-out” is the term applied to a system or procedure designed to control all situations where the unexpected energising, start-up or release of stored energy of the equipment, machinery or processes, would be likely to endanger or injure any personnel.

Occupational Health and Safety Regulations require that any person working on a machine for maintenance must secure all parts and attachments against inadvertent movement, where the work will expose workers to energy sources, the hazard must be effectively controlled, and the energy isolating devices must be locked out as required in these procedures.

Through compliance with this lock-out procedure, any person working on a piece of machinery for any period of time, can be assured of not being injured due to accidental or inadvertent engagement of any power supply system. The intention is to ensure that the machine or equipment is placed in a “zero energy state”.

For safety reasons, all persons must apply and remove their personal locks to ensure that everyone has stopped working and has cleared the area before energising the area or equipment again.

Access to areas were lock out conditions are in progress must be controlled and the person responsible for supervising the work must ensure that notice is given to adjacent areas or signs posted to prevent persons entering locked out areas until normal conditions have been restored.


The following definitions are applicable to these safe work procedures and regulations.


It is the responsibility of all persons engaged in any activity that requires special safety precautions to know and comply with the lock-out procedures. Failure to follow these lock-out procedures is cause for disciplinary action.

Supervisors and instructors are assigned the responsibility to ensure that all persons are adequately instructed in lock out procedures and that all energy sources for equipment and machinery are deactivated and secured in the “off” position through the use of appropriate locks.

Contractors or service technicians not permanent employees of the company are  responsible for providing their own locks. Under no circumstances will the company provide locks to non-employees.

Locks and Keys

Each authorised person must have their own locks issued by the department. These locks must be clearly marked and labelled or stamped with that person’s name in order to identify the owner of the locks.

No two people shall have matching keys.

No “extra” keys are to be retained by the Supervisor or any person other than the worker to whom the locks were assigned. No keys for lock-out locks shall be retained in any key cabinets.

In the event that a person’s keys are lost, the locks will be removed in accordance with the Lock Removal section of this procedure.

Any person who loses their keys and/or locks must report that loss to their Supervisor immediately. The person must be issued with a new lock to ensure no unauthorised person can unlock a lock used for lock out purposes.

Persons are forbidden to remove locks belonging to another employees. To do so will result in disciplinary action.

Under no circumstances are an individual’s personal locks to be loaned or borrowed.

PRIOR to removing the last lock from a control device, the person doing so is responsible to ensure that all other persons are clear of the machinery or equipment, and that it can be operated safely.

When going off shift and your personal lock is still in place, your relief must put his own personal lock on BEFORE YOU REMOVE YOURS.

Locks shall only be removed by the person who installed them. In the case of an emergency, see Lock Removal section of this Procedure.

The use of “Do Not Start” or “Lockout” tags in place of locks is prohibited.

Multiple Lock Attachments

Multiples lock attachments may be used. When a multiple lock attachment does not have enough openings for locks, an additional multiple lock attachment must be attached in close proximity to the original multiple lock attachment to ensure that it would be possible to clearly confirm that all workers have removed their locks before de-energising energy sources.

Maintenance Department Locks

Certain locks may be designated as “Maintenance Department Locks” or “Facilities Services Locks” for the purpose of securing equipment in an inoperable condition for long periods of time.

These locks shall be clearly different in size, shape and colour from the type of locks used by individuals.

These locks must be numbered consecutively and the total number available must be recorded.

Responsibility for the control of these locks and their keys must be assigned to one person only.

A register (log) shall be maintained to account for the whereabouts of these locks. Where they are signed out by the appropriate supervisor, the record shall indicate who signed the lock out and indicate where the lock is being used. Upon return, each lock shall be logged back in.

These locks shall not be used under any circumstance in place of personal locks.

Control Devices

Some means of attaching a lock and securing the control device in an inoperable position shall be provided for all types of control devices in the company. Where the control device is of a circuit breaker type, special lock-out devices shall be attached prior to the use of a multiple lock attachment and locks.

On circuit breaker panels, the use of the built-in lock on the panel cover door must  not be used for the purpose of lock-out. Doors of circuit breaker panels must be  fitted with a permanent hasp or eyelets which are capable of accepting a multiple lock attachment device. Specialised lock-out devices for use on individual circuit breakers are an acceptable alternative to this.

Where equipment is fitted with interlocks, those devices must be disabled and locked out in accordance with these requirements.

Plug-in Equipment

The only exception to the requirement for applying locks to control devices is when the equipment is connected to a wall or floor mounted socket or receptacle by a removable plug.

Before doing any maintenance work on such equipment remove the plug from the outlet.

Check that the correct plug has been removed by testing the equipment to ensure that it has been disconnected.

The person performing the work must keep control over this plug at all times.

Where more than one person is required to work on a piece of plug in equipment, a specialised plug lock box shall be attached to the free end of the cord and normal lock-out procedures shall be followed using multiple lock attachments.

Disengaging Power Sources

Before turning off the power source, check to ensure that no one is operating the equipment. A sudden loss of power could cause an accident.

If in doubt about the location of the main disconnect switch or the method of pulling it, contact the company person responsible for the area in which the equipment is used.

An electrical disconnect must not be disengaged (pulled) while it is under load. Such action can cause arcing or an explosion and result in injury or property damage.

When disengaging an electrical disconnect be sure that the machinery or equipment is first turned off at the controls. Open the main disconnect with your left hand and face away from the panel.

In larger high voltage installations only a qualified electrician should operate the main disconnect.

When locking out valves, taps, or items other than electrical disconnects, the appropriate multiple lock attachment shall be placed through the lock-out loop on the control. If a lock-out loop is not available, an alternate means (i.e. chain, specialised lock-out cover, etc.) shall be used to secure the control device in an inoperable position.

All accumulator tanks or reservoirs which could be holding sufficient reserve energy to operate the equipment must be drained prior to commencing maintenance work. The drain valve must be secured in the open position.

The removal of fuses for the sole purpose of disconnecting power is prohibited.

Locking Out – General

Locking out must be done by the first person to begin work on the machinery or equipment. That person must be responsible for “testing” the equipment to ensure that it is not functional prior to commencing any work.

Each person working on a piece of machinery or equipment, must apply their locks to lock-out all power sources. If three people are working on equipment, then three locks must be on each power source.

Locking of control switches or buttons is prohibited since it is not a positive disconnect.

If in doubt about lock-out rules or procedures ask your supervisor or Occupational Health and Safety Department staff.

Lock-Out Procedure

The following procedure must be followed for all machinery or equipment, (except plug-in equipment), where maintenance is required to be performed.

  • Shut off the machinery or equipment.
  • Shut off the power source(s) at the control device(s).
  • Place multiple lock attachment(s) in lock-out loop or alternate locking device. Combination locks cannot be used for this procedure.
  • Apply personal lock(s) to multiple lock attachment(s). Each personal lock must be marked or tagged to identify the person using it.
  • Procedures must be implemented for shift or personnel changes, including the orderly transfer of control of locked out energy isolating devices between outgoing and incoming people.
  • Test control buttons to be sure that the power source has been disconnected.
    • a. Push start button.
    • b. Push stop button.
  • Perform repairs and/or maintenance.
  • All employees working on a machine are to remove their lock(s) as soon as they have completed their maintenance.
  • Upon completion, clear away all tools and personnel.
  • Replace all guards and protective devices.
  • Ensure that everyone is clear of the machine and start the equipment to return it to normal.


When it is essential to the process that the equipment remain in operation to perform maintenance related work:

  • Only that part of the machinery which is vital to the operation shall be energised.
  • Workers engaged in such operations must be fully authorised and trained.
  • A separate written safe work procedure is developed and posted adjacent to the equipment.


Training in lock-out procedures must be provided to all persons who are required to use this or similar procedures by their immediate supervisor or other trained person.

If a person cannot demonstrate an understanding of the process or has violated the procedure, additional training and supervision will be required prior to being allowed to engage in any work activity which requires the protection of lock-out.

Group Lockout Procedure

If a large number of workers are working on machinery or equipment, or a large number of energy isolating devices must be locked out, the following group lockout procedure can be used.

In a group lockout procedure 2 qualified persons are responsible for:

  • Independently locking out to energy isolating devices
  • Securing the keys for the locks used with personal locks or other positive sealing devices deemed acceptable
  • Completing, signing and posting a checklist that identifies the machinery or equipment components covered by the lockout.

Prior to starting work, each worker must apply a personal lock to the key securing system.

Workers may lock out a secondary key securing system if 2 qualified workers lock out the primary key securing system and place their keys in the secondary system.

When work is completed, people remove their keys from the key securing system.

When it is determined that it is safe to end the group lockout, the 2 qualified persons can then remove their locks.

This procedure must be posted where the system is in use.

Lock Removal Procedure

Removing another employee’s lock is a serious matter and is prohibited except in the case of an emergency and only when this procedure has been followed:

  • The supervisor must be informed that a lock needs to be removed and that the person assigned the lock cannot be located
  • The supervisor will make every effort to contact the lock owner and document these attempts.  
  • The responsible line manager for the area must be informed of the lock removal and must ensure that all persons and equipment are safe before the supervisor may remove the lock.
  • If the person cannot be located and the area in question has been inspected and is clear of any hazards to anyone, the supervisor overseeing the work may instruct someone to cut off the lock.

Locks Not Required

Locks are not required if the energy isolating device is under the direct control of a single worker at all times while working on the machinery or equipment.

When a tool, machine or piece of equipment receives power through a readily disconnected supply such as an electrical cord or quick release air or hydraulic line is disconnected from its power supply and its connection is kept under the immediate control of the worker at all times while the work is being completed, no lock is required.