Isolation for maintanance work
Isolation of any energy sources before maintanance


The basic concept of the positive isolation

My life is my life:

  1. Assurance for the correct positive isolation
  • Energy source identification
  • Accreditation/authorization for isolating persons
  1. Assurance that equipment cannot be energized till the person has completed the job
  • Personal lock
  • System locks

Basic concepts of positive isolation – energy source identification


  1. To have established and approved procedure in writing.
  2. The document can be referred both by the isolating agency and the agency asking for isolation

Contents: for various types of maintenance job for each equipment:

  1. Isolation point
  2. Method of isolation
  3. The locking point


The sample format for Energy Source identification (Having Single energy source Electrical)

Format of electrical isolation


  1. In the method of isolation The detail of isolation( like breaker to be racked out, discharging to be done, permanent earthing to be done at particular location etc.) The list of switchgear put in the safe position to be mentioned.
  2. The type of job may be categorised based on the basic philosophy which may affect the electrical isolation method. Like the jobs which may not require direct exposure to electrical parts.
  3. No column shall be left blank. If some column is not applicable in the particular case then “NA” shall be written to ensure that it is not simply a miss but a considered view.

Energy source identification- An example

Department: XYZ                            section:PPE


Isolation energy identification

The basic concept of Positive isolation- An example

Formats for energy source identification (having multiple energy sources or single energy source other than electrical)



Basic concept of Positive isolation- An example


  1. In a method of isolation, The details of isolation (Like breaker to be racked out, the valve is to be closed, the pump is to be switched off) to be done shall be mentioned.
  2. No column shall be left blank. If some column is not applicable in a particular case then “NA” shall be written to ensure that it is not simply a miss but a considered view.


  • Chief/head of each department shall identify the authorised persons for giving the isolation for each type of jobs.
  • An approved list of authorised persons shall be maintained in the department as a Quality document.



  • Protected person: those who will attach their personal lock to an isolator or a group isolation box for doing the job on equipment.
  • Isolating person: A person who performs isolation and who is authorised under this procedure.
  • Isolation planners: isolation planners shall be responsible for preparing and maintaining the isolation procedure for the complex isolation and energy source identification document for the particular discipline of the department.
  • Isolation training level 1: A training course for protected persons covering the isolation locking regulations.
  • Isolation training level 1A: A training course for isolating persons.
  • Isolation training level 2: A training course for isolating planners.
  • All client Employees who may work under the permit shall be Trained for……isolation training level-1.
  • All contractor’s supervisors who may work under the permit shall be Trained for…..isolation training level-1.
  • All isolating persons shall be trained…..isolation training level-1A.
  • All isolation planners shall be trained…..isolation training level-2.

The right of the protected person

  1. He can ask for the trial to ensure that correct isolation has been done.
  2. He can refer to energy source documents to ensure that correct isolator are put in safe condition.
  3. He can refer to the authorization list to ensure that a competent person is giving isolation.

Type of positive isolation locks

  1. Personal lock(Red) for client Employee.
  2. Personal lock (Blue) for contractor’s supervisor only.
  3. Equipment Lock (Yellow) for – attached at isolator by isolation person.
  4. Group board lock (Black) for locking the group isolation box.


Specification of locks:-

  • Each lock shall have a single key.
  • The lock shall be engraved with the unique number which shall help in tracing.
  • Locks shall have a groove in which the identification label shall be fixed.
  • Locks shall have long and thin shackles.
  • The lock shall be of four colors black, red, yellow and blue for board identification.

Scissor locking device:

Scissor locking in isolation

General rules for isolation locks

  1. Isolation locks shall not have duplicate keys. If required these shall be cut to open as per procedure.
  2. No lock shall be used for any other purpose than for which is meant.
  3. Never attempt to bypass an isolator when isolation lock is attached.
  4. Isolator must be locked in a “SAFE” position.
  5. Isolation locks shall never be used to ensure isolators in the non-isolation position.
  6. Never attached a lock to another lock.

Identification of personal locks

  1. Personal lock shall be identified through stickers pasted on the locks.
  2. Sticker for client Employee shall bear information; P.NO., Department/section.
  3. Sticker for contractors supervisor shall bear information; name, Contractor’s name, contact tel.no.


Method of isolation

Control stop— isolation;

Individual—- isolator isolation;

Group isolation;

Isolation for working alone

Control stop—

  • Shall be used for low Risk, short duration, routine operation job.
  • Shall not be used on high voltage.
  • All the control stop jobs shall be documented & approved by Head operation and safety.
  • The control stop document enlists all the precautions while doing the specific job.
  • No permits and locking is to be used for control stop
  • Any job not appearing in the document cannot be done under control stop procedure.

Individual isolator isolation—this method shall be used when:

  • When isolation is to be done at the single place and;
  • The agencies asking for isolation may be allowed to enter the area for putting personal lock without any risk to the plant, machinery, human safety, and MA operation.

Group isolation— this method shall be used when:

  • When isolation is to be done at more than two places or;
  • Some of the agencies asking for isolation cannot be allowed to enter the locking area for putting personal locks.


Procedure for group isolation

  • The isolating agency carries out isolation as per the procedure and put equipment lock at each isolator.
  • The key of each isolator are put in the group isolation box and the group lock is put there.
  • All the working agency shall put their personal safety locks at the group isolation box after the group lock is placed.

Ownerships of locks (Red & Blue)

  • The personal lock both for client Employees and the contractor’s supervisor shall be owned by the individual and shall be used as per the regulation of this standard.
  • Each individual shall maintain their personal lock. It shall be treated as important as the gate pass for each individual.

The issue of the personal lock to client Employees

  • After getting the locks through stores in the department the locks shall be issued centrally through the department.
  • Each person shall be issued one personal lock.
  • Each lock bears one permanent unique number. The lock shall be issued to the individual person vide his written receipt along with the serial numbers of the lock. This record shall be maintained in the department, preferably in a resister which should be a Quality system document.
  • In case the employee is transferred to another department inside other work then he shall carry the same personal lock along with him. The necessary changes shall be incorporated in the records of both the departments.
  • In case the employee is transferred outside other works then he will surrender his lock in the department. The department shall make the necessary changes in the records and keep this lock as spare.


The issue of the personal lock to contractors Employees

  • Central agency of the department shall get these locks from the store.
  • Each sectional head shall take the number of locks as per the requirements of his section from the central agency if department.
  • The contractors shall get the locks from the department head/sectional head on a returnable basis for their supervisors.
  • The department head/section shall keep the record of the number of locks given to particular contractor along with their serial numbers.
  • Contractors shall be advised to keep the record of the serial number of each lock given to their respective supervisors, which may be cross-checked by client offices.

Step for personal locking (Both Red &Blue locks) before commencing the work.

  • Ensure that isolating person carried out the isolation of the same equipment on which the person is going to work.
  • Ensure that isolation covers the boundary of his work.
  • For the group, isolation attaches a personal lock to the group isolation box with a group isolation lock attached.
  • For “Individual isolator isolation” attach the personal lock to the multi-lock device with an equipment lock attached.

Before leaving the job site:

  • Client employees must remove your personal lock before leaving the job site.
  • Contractor’s supervisors shall remove their personal lock only when all of the workers under him has completed the job and left the job site.


Rules for the personal locks (Red & Blue)

  • Ensure that there is an equipment lock (yellow) if the personal lock is being on a equipment.
  • Ensure that there is a group lock (Black) if the personal lock is being put on a group isolation box.
  • Even if isolating persons is a part of the work crew, he will place his personal lock.
  • Always attach your own personal lock.
  • Never attach another person’s lock.
  • Never depend on someone else’s personal lock for your personal protection.
  • Never lend your personal lock to anyone else.
  • Never remove a personal lock from an isolator/ group box other than one bearing your name.
  • Never deface or paint the isolation locks.

Also visit for – Positive Isolation?


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