Your Guide to the LOTOTO Procedure: Safety for Everyone

When it comes to fixing, cleaning, or performing maintenance on industrial machines, the most serious threat is not the tool you are using, but the energy the machine normally runs on. That energy—whether it’s electricity, pressurized air, steam, or even a heavy part held up by gravity—can seriously injure or kill a worker if it is suddenly or accidentally released.¹

To prevent these tragedies, every modern workplace relies on a formal, step-by-step safety system.² The most complete version of this system is known as the LOTOTO procedure, which stands for Lockout, Tagout, Tryout.³ It is simply a promise to the worker: before you put your hands on this machine, we will make sure it is completely and totally dead.

This procedure is not complicated, but it must be followed perfectly every single time. Here is a simple breakdown of the process.

Phase 1: Planning and Telling Everyone

Before the machine is even touched, the person in charge of the maintenance (the “authorized employee”) must make preparations and inform the necessary people.⁴

Step 1: Know Your Machine and Plan the Work

The first job is to understand the equipment inside and out. The authorized person must know exactly what kind of energy the machine uses—Is it electrical?5 Hydraulic? Mechanical?—and exactly where every single energy source is located. They must have a clear, written plan for the shutdown.6

Step 2: Tell Everyone You’re Starting

Communication is key. The authorized employee must notify all “affected employees”—the people who operate the machine or work nearby—that the equipment is going to be shut down.7 They need to know what machine, why, and for how long (roughly).8 This is to stop anyone from getting confused and accidentally trying to start the machine up again later.

Phase 2: Killing the Power

This is the central part of the LOTOTO procedure—physically stopping all energy to the machine.⁹

Step 3: Shut Down the Machine Safely

The authorized employee must turn off the machine following its standard, normal shutdown process.10 They should not use the emergency stop button for this, as a proper, orderly shutdown is necessary to prevent other issues and to make sure no energy is trapped.

Step 4: Isolate Every Energy Source

Now, the actual disconnection happens. For electricity, they must flip the main circuit breaker.11 For steam or air, they must close the main valve. The goal is to separate the machine from its power source at the nearest disconnection point.

Step 5: Lockout (L) – Applying the Physical Block

After isolation, the authorized employee applies a physical Lockout device—a strong, dedicated safety padlock—to the energy-isolating switch or valve.12 This lock holds the device in the “off” position.13 Crucially, if there are multiple people working, each person places their own personal lock on the isolation point. This gives every individual worker a personal guarantee that only they can remove their lock and restore the power.

Step 6: Tagout (T) – Applying the Warning Sign

Immediately after the lock, a Tagout device—a durable, highly visible warning tag—is attached.14 This tag serves as a clear sign that the machine is locked out and warns everyone not to touch the controls. The tag usually includes the name of the authorized employee who applied the lock and the date, acting as a clear, formal warning.15

Step 7: Deal with Stored Energy

Many machines hold power even after the main supply is cut. This is “stored energy.” It could be pressurized air in a line, fluid in a hydraulic cylinder, or a spring under heavy tension.16 The authorized employee must find, release, vent, or block all of this residual energy.17 For instance, air might be bled from a line until the pressure gauge reads zero, or a raised machine part might be secured with a physical block.

Phase 3: The Ultimate Check and Final Work

The job is not safe until this final test is done.¹⁸ This is what truly separates this method and defines the full LOTOTO procedure.

Step 8: Tryout (T) – The Verification Test

With the locks and tags in place and all stored energy gone, the authorized employee must now try to start the machine using its normal operating controls.19 If the system is truly safe, nothing will happen—the machine will not turn on, move, or show any sign of life.20 If it does, the employee must immediately stop, step back, and figure out what energy source was missed, then repeat the whole process. This test is the final, non-negotiable step that confirms the machine is at a “zero energy state.”21

Only after a successful Tryout can the worker begin the actual maintenance, repair, or cleaning task.²² This systematic approach ensures maximum safety and confidence for the worker.²³