Knowledge · Fundamentals
What is LOTOTO (lockout – tagout – Tryout)?
LOTOTO always starts from a specific piece of equipment, its identified energy sources and an approved work procedure. This page explains the individual steps, what Tryout means and why an approved permit is not enough on its own to start work.
A lock confirms the action, not the result. Tryout verifies that.
What does LOTOTO mean?
Short answerLOTOTO stands for three steps: lockout (locking), tagout (tagging) and Tryout (verifying that the isolation is effective).
The principle is the same as in LOTO. LOTOTO, however, puts verification of the isolation into the name itself. That makes it a separate, named step which is hard to overlook. The difference between the two terms is summarised in LOTO vs. LOTOTO.
What is Tryout and why is it a separate step?
Short answerTryout is verification that the isolation of the energy sources is actually effective. It is a separate step because a lock confirms that an action was taken, not that it achieved its purpose.
A lock on a disconnector shows that someone operated and secured that disconnector. It does not show whether it was the right one, whether the equipment has another supply, or whether pressure remains in the system. Only verification at the equipment answers those questions.
Depending on the type of energy, Tryout may include, for example:
- attempting to start the equipment with the normal controls, which must fail,
- testing for absence of voltage by an authorised person with a suitable instrument,
- checking that pressure in the hydraulic or pneumatic system is at zero,
- checking that moving parts are at rest and secured against movement.
After verification, the controls are returned to the off position so that the equipment cannot start unexpectedly when it is unlocked. Where hazardous energy could build up again during the work, verification continues as the conditions of the job require. The exact method is set by the procedure for the equipment and carried out by a competent person.
How Tryout is recorded and built into the digital workflow is something we design according to the rules of each plant. Technically, it makes sense to link the record to the equipment or isolation point, the person, the time and the result of the verification.
How does the LOTOTO procedure run?
Short answerFrom preparing and approving the job, through isolation, lockout, tagout and tryout, to the work itself, its completion, unlocking and returning the equipment to service.
- 01RequestEquipment, energies and isolators
- 02ApprovalPerson responsible for the area
- 03Isolation of each energyEach energy is confirmed by its isolator
- 04TryoutVerifying that isolation is effective
- 05WorkFurther groups join the lockout
- 06All groups finish workWhile a group is active, unlocking is not possible
- 07UnlockingEnergy by energy
- 08Archive and audit trailThe history of the job remains traceable
- PreparationThe equipment, type of work, energy sources and the people responsible for each action are defined.
- ApprovalAn authorised person reviews the prepared job and gives consent under the plant’s rules.
- Isolation and lockoutEach energy source is disconnected at its isolation point and secured with a lock.
- TagoutTags with details of the isolation are attached to the isolation points.
- TryoutIt is verified that the isolation is effective and residual energy has been released.
- WorkThe workers carry out the job, each protected by their own lock.
- Completion and unlockingOnce all work is finished, locks and tags are removed and the equipment returns to service.
How individual energy sources are isolated, and why it pays to confirm each one separately, is explained on the energy isolation page.
Why is an approved permit not enough?
Short answerBecause approving a permit, carrying out the isolation and verifying that it works are three distinct actions with different meanings and different responsibilities.
When these actions merge into a single signature, it is easy for an administrative approval to be mistaken for meeting every condition. The process should therefore keep them clearly separate, whether on paper or digitally. How this works with a digital permit to work is described on a separate page.
ReadDigital permit to workWhat happens when the work ends and the equipment is unlocked?
Short answerBefore unlocking, it must be confirmed that every worker and work group has finished, the work area is in order and affected people have been informed.
Unlocking is a critical moment. The equipment returns to a state in which it can start, and nobody may remain in the danger zone. Checks cover removal of tools, refitting of guards and restoration of safety devices.
On larger jobs, several groups work on the equipment at the same time or one after another. Each must finish before the equipment is unlocked. How to keep track of active groups is covered on the group lockout page. At shift changes, continuity of physical protection must be maintained according to the defined procedure.
Can LOTOTO be digitalised?
Short answerYes – the records, the sequence of steps, authorisations and the coordination of people. Physical lockout, tagout and tryout remain tasks performed at the equipment.
A digital process can record who secured which energy and with which lock. The overall “locked” status appears only once every energy has been confirmed. Further work groups can join the lockout, and the equipment cannot be unlocked while any of them is still active. All of this follows the rules your plant already uses.
More on what can be digitalised and where the limits lie is on the digital LOTOTO page.
Frequently asked questions
Is Tryout also part of conventional LOTO?
Verifying that the isolation is effective is always part of hazardous energy control. The term LOTOTO simply names it explicitly as a separate step.
Who carries out Tryout?
A competent person, following the procedure for the equipment concerned. Who exactly that is depends on the plant’s internal rules.
Is Tryout done separately for each energy?
The isolation of every energy source that was isolated needs to be verified. The method and order are set by the procedure for the specific equipment.
Does LOTOTO.digital record Tryout?
How Tryout is recorded and built into the digital workflow is something we design according to the rules of each plant.
Next step
Show us your LOTOTO procedure.
We will go through each step with you, including Tryout, and propose how to manage them digitally in line with your plant’s rules.