PLC Training - Lockout Tagout (LOTO)
Lockout Tagout (LOTO) is a set of procedures that should be followed to properly shut off machines and assure they are not able to be started up again until authorized persons allow it.
It is a procedure for controlling hazardous energy sources from electrical, mechanical, hydraulic, pneumatic, chemical, thermal, or other sources in machines and equipment that can be harmful to you and your surroundings.
In simple terms, doing these things will save your life. The majority of accidents happen when standard operating procedures are not being followed such as maintenance, troubleshooting, and testing.
It is important for everyone that is working on a machine to follow their own lockout tagout procedure. Just because one person has followed the lockout tagout procedure doesn't mean that everyone is safe. The video to the RIGHT is a humorous but good example of the dangers of relying on someone elses lockout tagout to keep you safe.
Also for our instructors and students following this series of lessons with our PLC Trainers, DO NOT think that you can skip this lesson until you are in the workforce. These are important skills that should be followed from the beginning. Plus, for students using our more advanced trainers that include wiring exercises, these procedures just may keep your fellow student from accidentally plugging your trainer in instead of theirs and shocking you while you're wiring yours.
Lockout Tagout procedures are constantly improving so we recommend you check the latest safety standards such as Occupational Safety and Health Administration (OSHA) standard and the NFPA 70E which is specifically for electrical. OSHA CFR 1910.147 spells out the step by step requirement for lockout tagout. Reading it can be intimidating. Below are the procedures for a basic machine. It is based off of NFPA 70E and only covers electrical. A reminder to check and follow all applicable standards.
1. Communicate - Make sure everyone affected knows that you are preparing to lock the machine out, the reason, and for approximately how long. This one isn't in most procedures and will be the most important thing you can do in means of keeping yourself safe. It is important for contractors working in plants where they may not be familiar with all procedures.
2. Disconnect - De-energize all sources of electricity from the equipment. Machines with multiple energy sources are supposed to be labeled as such, but always be on the lookout for additional conduits that seem to leave the machine that could contain voltages from other sources.
3. Release or Contain Stored Energy - Machines may have capacitors with special instructions or additional wait time needed before servicing equipment. Also, machines can store up mechanical energy in the form of flywheels, pneumatics, and hydraulics, that either must be bled off (release) or contained such as is the case when mechanical jacks have to be put in place to prevent mechanical movement.
4. Lockout and/or Tagout - In most cases, you will apply a lock and a tag to the main disconnect of the machine. There are instances when you can't disconnect the power and can only tagout a machine. These instances usually require additional procedures to be followed. Another note for contractors, while most tags do not have a field for this, it is very helpful to include a cell number on the tag so personnel in the plant can contact you immediately. This has prevented dangerous situations more than once where plants had wrongly assumed you had left for the day and you had only ran out to grab some parts.
5. Checkout - This is the most missed step of a basic lockout tagout procedure. Check to make sure the energy is disconnected. Make sure the disconnect won't operate with the lockout in place. Check that all lights and screens on the machines went out. It isn't uncommon for them to be powered from different sources. In addition to taking a volt meter such a this one and checking that the main power is disconnected, keep one of these non-contact voltage testers with you to occasionally check items that may have stored energy or separate power sources.
6. Perform Work - The lockout tagout should remain in place until work is completed including if you leave for lunch, the night, or the weekend.
7. Remove Lockout and/or Tagout - Remove and do any testing required to place the machine back into service. Make sure no additional tags should be put on the machine such as "Waiting on Engineering Approval" or "Waiting on Safety Review".
8. Communicate AGAIN - Let people know when you are finished. If they know you tell them when you finish work, then they are less likely to try to start a machine before you come to them.
Lockout Tagout is not only required when working on equipment, it very well may save your life one day. In the next lesson you will get familiar with the components of your trainer.
Go to the PLC Training Getting Started Lesson series to select your next lesson. There are also many other Lesson Series on PLC Programming and Industrial Automation.