What is Electrical Lockout Tag out System?
Electrical Lockout Tag out procedure, also referred to as LOTO, is a safety isolation system for electrical power, to prevent unsafe operation or energizing electrical equipment which is under maintenance or out of service for safety purposes.
Isolating any type of energy at workplace , not only electrical energy, requires implementing a LOTO procedure, to ensure safety of workers and affected persons.
Why is using Lock-out tag-out important?
I was a fresh graduated electrical engineer, I joined a factory of plastic pipes to work for. Unfortunately, the factory gave no attention to safety.
Back then, I had zero safety culture. While We, me and 2 electricians, were working on an electrical fault that required power isolation.
Of course, we did power isolation, the wrong way of course, we absolutely didn’t use LOTO.
We just switched off the circuit breaker. Accidentally, I switched it on back before the 2 electricians finish the work.
The good news, I realized this big unsafe condition before any one got shocked. It was a nightmare that I couldn’t forget all my life.
But, I got the message. Now, Safety is my priority, LOTO is a must. I never skip safety at my work.
When I conduct a safety inspection with safety team, I can see safety hazards that others can’t see. I’m one of the most active safety issues reporter among my team.
Using lock out and tag out (LOTO) is important because, It prevents unsafe operation of the equipment, and protects the authorized person during the work on the equipment by the following:
- Ensures isolation of all possible power sources.
- Informing all affected persons, to prevent any power connection by them.
- Tagging out informs any other person to know that the equipment is out of service.
- Prevents accidental electrical short circuit during maintenance.
- Working on an isolating equipment makes the maintenance team work without any fear of accidental operation.
Is Lock out and tag out the same?
Lock out is not the same as tag out. They are different actions that are required when isolating energy.
Lock out is to shut the energy source off. While using a tag to inform others about the status of the equipment and isolation information.
Setting the tag out is the second half of the energy isolation process, It comes after Locking the equipment out.
Lock out Tag out Basics
Isolating electrical power must be taken seriously, all workers must pay attention before isolating electrical power.
Electrical LOTO starts before job starting, by identifying all possible electrical hazards and power sources in the equipment.
Some equipment are fed only by one power supply, while in some special cases there are more than one power source which must be electrically isolated.
After isolating electrical power, a safety padlock and tag out, must be a part of the power isolation.
The safety padlock is a color coded padlock with only one safety key.
When multiple workers of different departments are working on the same equipment, each department must use its color coded padlock and tag on the power source.
Important rule: Never ever count on other department’s isolation LOTO, and always use your own padlock and lockout tag out for your job.
A standard tag label should has details of worker name, phone number, department, and the date and reason of power isolation.
These information are important and must be correct and clear.
Who is affected person by power isolation?
Workers at the workplace are divided into authorized and affected workers.
An authorized person is a person with enough experience and knowledge to engage in hazardous electrical energy isolation and control.
The authorized worker is mainly performing the proper maintenance and work on the equipment.
He also, the one in charge to put padlock and tag on the power source. Also, he is the only one who has the authority to remove the isolation and LOTO after work finishing.
While the affected person is any person who will affect by the electrical power isolation, he is not involved in the isolation and LOTO procedure.
Affected person must be informed before the isolation process starting, because he may try to re-energize the equipment to complete his regular work.
If the work on the equipment will remain to the other shift, A good LOTO should inform the other team about the isolation reason and time.
How to perform Electrical LOTO?
However, a general LOTO procedure can play out like this:
- Authorized person must identify electrical sources feeding the equipment and how to control them.
- All affected workers should be informed about the power isolation as follows:
- The equipment which will be isolated.
- Isolation reason.
- How long time expected for this work.
- Contact person for more information.
- Authorized person to shut down the machine, Isolate electrical energy, Remove any stored energy and double check the isolation by AVO-meter and testers.
- All workers on the equipment apply their color coded padlocks and tags.
- One more time authorized person verify the isolation process by trying to operate the machine while LOTO is already applied. In this case the operation trial must fail and no power connection occurs.
- After performing maintenance and work all workers must make sure that hand tools and materials have been removed before removing isolation.
- Each worker will remove his own LOTO (padlock and tag).
- Before energizing the equipment all authorized and affected workers must be notified that power will re-energized to the equipment.
Any changes of the isolation and maintenance plan should be recorded an sent to all affected persons. Informing them the new plan and time of the isolation.
My coworker in a factory told me that once upon a time, a maintenance worker was working on a heavy mixer.
The worker isolated power without LOTO system at all. While he was working on the equipment some one else restarted the mixer and the maintenance worker lost his two legs.
How to perform Electrical LOTO for a portable generator?
Electrical portable generator lockout and tagout depends on the work required. If we require the isolation to make maintenance for the generator it self, then isolating the generator main circuit breaker is useless.
How come to isolate the output power of the generator while your work is on the generator parts. Its a fatal mistake! isn’t it.
Let me explain it to you! If you apply a good LOTO to the output circuit breaker of the generator, while you are working on the generator cooling fan, If the generator run accidentally the fan will rotate and you may get hurt. No matter what type of LOTO is applied to the circuit breaker.
Your work on the generator parts
In this case, working on the generator parts, We isolate the batteries of the generator. and use a plug LOTO for it.
Set a tagout on the generator start button. Notifying all isolation data, reason and timing.
By applying this battery isolation and using a LOTO, the generator has no chance to run. It requires batteries to run.
A good point to consider is to make sure the generator has no other DC source parallel to the batteries, i.e a backup DC source. In my work we have generators with two DC sources. In this case you should isolate and apply LOTO for the other source.
Try to run the generator after applying the isolation and lockout and tagout. It shouldn’t run.
Your work on the load
In case your work is not on the generator parts, but on a load of the generator, apply double isolation.
I mean, isolate the battery and the circuit breaker. Use lockou/tagout for each of them. Try to run the generator.
In both cases Set the start button on the OFF position and use a tagout on it.
How to perform Electrical LOTO for a Overhead Power lines?
When working on overhead power lines, making a repair like replacing insulator, we isolate power from one of two positions.
If its possible, we isolate power source by switching off the main circuit breaker at the switch gear. Its easy to perform LOTO for the circuit breaker.
In case of we can’t isolate the circuit breaker, for any reason, we isolate the part of the overhead power line network by isolating the cutout fuse of this part.
In some cases we perform LOTO on the pole itself.
The good thing in case of overhead power lines, is the affected persons can’t restore power. How can they re-close a medium voltage fuse? Its almost not possible!
However we should apply a LOTO as possible, inform all Authorized members at the location about the task, to ensure they won’t close the fuse. Authorized persons can do it as they have all required tools and knowledge.
A safety precaution when working on OHTL, is to use a medium voltage tester and apply grounding for the three phases before your working location.
If power restored accidentally, the grounding will protect you and the fuse will blow or the circuit breaker will trip.
How to remove Lockout and Tag out?
The removing of LOTO should be a controlled well organized process. This process is just as important as the isolation process is.
If we remove the LOTO without following safety rules, we can cause what we use LOTO to prevent, i.e injuries due to accidental operation.
After you finish you work, follow the procedure of LOTO removal:
- Remove all hand tools, its better to have tools check list to ensure no tools remain inside the equipment.
- Check all team members. Make sure all of them finished and no tools or persons remains behind.
- Notify all affected persons.
- Remove LOTO.
- Contact affected persons again.
- Contact all other maintenance teams on the job.
- Visually inspect the work area.
- Restore the power.
- Record power isolation in the LOTO data sheet.
A common mistake happens after LOTO removal, when some one forget a tool and go to bring it back. Its risky, never do that, and never allow any one of your team to do so, No exceptions.
Its important to double notify affected persons and other team members before power removal, make sure all things as it should be.
Never hesitate to apply lock out and tag out again if some one asked for going back to bring his tools. Its much better to wait some more minuets rather than send some one to a certain risk.
who should remove a lockout/tagout?
The authorized person who involved in the power isolation should only apply power restore and remove the LOTO.
In fact he should keep the isolation padlock key while he is performing the maintenance work on the equipment.
If this not applicable for any reason, like the maintenance and power isolation remains to the other shift, another authorized person can remove the isolation. In fact he should read all associated information about the isolation reason, time and affected persons.
A rule of thumb is, this who will remove power isolation must be:
- Aware of all affected persons and know how to contact all of them.
- Aware of power restore procedure.
- Aware of all participants and workers, i.e other teams on the job.
- Visually inspect the work area.
LOTO system station and datasheet
All isolation processes must be recorded in details in a specific datasheet. This recording will be a good reference and history to track all electrical power safety isolation.
Also it will be a strong way to track safety padlocks at all workplace location. The record must contain the following data:
- Isolation authorized person name.
- Isolation date and hour.
- Isolated and tagged equipment.
- Isolation reason.
- Safety padlock serial number.
- Any related remarks.
All safety padlocks, tags and isolation devices and accessories should be stored in a controlled station (i.e cupboard).
One or more supervisors should be in charge of this lockout tag out station, and are responsible for recording and tracking all isolation data.
Electrical Lockout Tagout devices and accessories
Electrical panels are normally attached with a lock eye to put the safety padlock when isolating power.
But some times the job requires just isolating one circuit breaker while the panel has multi loads circuit breakers which will not isolated with in the job.
In this case we need to isolate the required circuit breaker only, But how to isolate CB while it has no eye or opening for padlocks? In this case we use a CB lockout device.
- For miniature circuit breakers isolation, the below device is used.
- For small sized power plugs we can use a special isolating tool below.
- For large size power plugs we use the following isolation tool.
When LOTO is not applicable?
In many cases we can’t apply LOTO for electrical energy. How can I apply power isolation for an equipment which I need to check a wiring fault? I need power on to troubleshoot the equipment, and to find out where the faulty device is!
In this case we work on live power. Yep, its risky! this is why only well trained authorized electricians and electrical engineers are allowed to do such jobs.
Of course we do such jobs with great precautions and electrical safety rules. We use insulated tools, wear PPE and some more precautions that I have written in detailed in my article, How electricians Work On Live Parts? you can read it for more information.
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