Lockout/Tagout Basics

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Locking out and tagging equipment is one of the most basic safety procedures in general industry and maintenance work, especially in larger buildings. The HVAC and refrigeration industries have lots of equipment with moving parts, electrical circuits, and other hazards. These machines can severely injure or kill workers if someone energizes them while workers operate on them. 

Some technicians may think that the lockout/tag-out procedure is overkill, but it can save many lives. On the employers’ side, OSHA can also slap heavy fines on organizations that lack proper lockout/tagout programs. In fact, according to OSHA’s official data and statistics, lockout/tag-out violations were the 6th most common source of citations in the 2020 fiscal year.

Lockout/tagout, also known as LOTO, is a set of procedures that either forbids the equipment from being energized without authorization or warns other people that someone is working on the system. If used correctly, these methods may be the difference between life and death.


Lockout vs. tagout

Although lockout and tagout are very similar and fall under the same safety umbrella, there is a critical distinction between them. 

Lockout occurs when a worker completely locks a machine out of its power source. Unless someone removes or breaks that lock, the machine cannot be energized while it is locked out. In most cases, lockout devices may only be removed by the person who applied the lockout device. That is because these devices usually require a key, though a person may break them with extraordinary force. (You would need heavy-duty bolt cutters and an immense amount of pressure to break these locks. It’s not like any ordinary cutting tool can break a lockout device.)

Many lockout kits have a hasp with several holes. These hasps allow multiple employees to lock a piece of equipment. This feature comes in handy when several people must repair or maintain a machine. Nobody can energize the equipment until all workers have removed their locks. A worker who continues working after everyone leaves will not be in danger because the machine cannot be energized until he removes his lockout device.

Tagout occurs when a worker fastens a set of tags near the power source. The purpose of tagout is to warn other workers that somebody is working on the system. It exists to deter other workers from powering the machine on, but it doesn’t physically stop them. The tagout method doesn’t lock power out and relies on other workers’ observational skills (and good intentions). It can only offer similar protection to a lockout program if everyone complies with the tagout program’s safety standards. As such, it is not as ideal as the lockout method. Tagout materials must also have text with clear instructions, such as “Do Not Start” or “Do Not Open.”

If a lockout isn’t possible, it’s still better to use the tagout method than nothing at all. OSHA recognizes the lockout method’s superiority, but it also requires employers to set forth a tagout procedure when locking out is infeasible.


LOTO procedure

According to OSHA, the LOTO procedure has six main steps, regardless if you use the lockout or tagout method:

  1. Prepare for shutdown.
  2. Shut down the system.
  3. Disconnect or isolate the machine from the energy source(s).
  4. Apply the lockout or tagout device(s) to the energy-isolating device(s).
  5. Release, restrain, or otherwise render safe all potentially hazardous stored or residual energy. If a possibility exists for reaccumulation of hazardous energy, regularly verify during the service and maintenance that such energy has not reaccumulated to hazardous levels.
  6. Verify the isolation and de-energization of the machine.


LOTO programs and products

OSHA requires employers to have a LOTO program in place. One of the main components of a LOTO program is proper training. Before any employees conduct work on equipment that must be isolated from its energy source, they need to undergo lockout/tagout training. Employers are also required to issue retraining whenever they modify their LOTO program, and employees must review the company’s LOTO programs at least annually.

You can also purchase LOTO kits with lockout materials (locks, keys, and hasps), writable and waterproof tagout devices, and non-reusable tagout device attachments (such as nylon zip-ties). These can be a bit expensive, but you’ll certainly be a lot safer if you carry one on your truck and use them in compliance with your company’s LOTO program.


Maybe you’re just an employee who wants to walk away from a job site with all your limbs intact. Perhaps you’re an employer who doesn’t want OSHA to slap you with a fine. Regardless of your involvement in the industry, lockout/tagout is a basic but effective safety measure that you should know. Its goal—and OSHA’s mission as a whole—is to protect human life on the job. 

If you would like to learn more about OSHA’s standards or your rights as a worker, please visit OSHA’s website. Some of the links below are OSHA resources specific to lockout/tagout.

Link to OSHA’s Control of Hazardous Energy Lockout/Tagout publication

Link to OSHA’s overview of lockout/tagout and directory resources



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