LOTO vs LOTOTO: what’s the difference and why does it matter?

LOTO and LOTOTO are both safety procedures used to prevent the uncontrolled release of hazardous energy during maintenance, cleaning or repair of machinery and equipment.

When applied correctly, LOTOTO ensures that equipment is fully isolated, cannot be restarted, and is verified as safe before work begins.

In the UK, the principles behind safe isolation are supported by the Health and Safety at Work etc. Act 1974, which places a legal duty on employers to ensure the health, safety and welfare of employees. Other legislation such as PUWER 1998 and the Electricity at Work Regulations 1989 reinforce the need for safe systems of work and effective control of hazards.

LOTO Meaning: Lock Out / Tag Out

Lock Out / Tag Out is a procedure which was implemented in Electricity at Work Regulations 1989 to protect workers from danger by keeping hazards isolated and locked away.

The main aim is to control hazardous energy by removing the chance of human error.

LOTO involves:

1. Locking out the energy-isolating device.
2. Tagging out the device with a warning tag.

This ensures equipment cannot be switched back on unintentionally while work is being carried out.

LOTOTO Meaning: Lock Out / Tag Out / Try Out

The procedure has now been updated to include an additional step before work can commence. This step removes the possibility of human error, or simple machine malfunctions, from causing injury during non-routine activities involving industrial machinery and equipment.

LOTOTO involves:

1. Locking out the energy-isolating device.
2. Tagging out the device with a warning tag.
3. Try out the equipment (attempt to start it after following lock out and tag out).

The “Try Out” stage is crucial as it verifies that the equipment has been de-energised and isolated.

This additional control measure confirms that the equipment has been correctly isolated and ensures there will be no accidental start-up during the process.

LOTO vs LOTOTO: key differences

Why the “Try Out” stage is critical

The key difference between LOTO and LOTOTO is the verification step.

Without testing the equipment, there is always a risk that:

• the wrong isolation point has been used;
• stored or secondary energy sources remain;
• equipment faults or failures exist;
• human error has occurred.

The “Try Out” stage helps identify these failures before an individual can be injured or killed.

It is now widely considered best practice and helps ensure businesses are meeting their legal duties.

LOTOTO process: step-by-step

A structured LOTOTO process helps ensure consistency and compliance. While procedures may vary depending on the equipment, a typical process includes:

1. Notify affected employees
2. Identify equipment, hazards and energy sources
3. Shut down the equipment safely
4. Isolate all energy sources (electrical, hydraulic, pneumatic, etc.)
5. Apply lockout and tagout devices
6. Control or release stored energy
7. Verify isolation (try out / test)
8. Carry out the work safely
9. Remove controls and restart equipment safely

The verification stage acts as a fail-safe, ensuring isolation measures are actually effective before any work begins.

Why would LOTO fail?

Common causes of LOTO failures include:

• Inadequate training or supervision
• Missing or defective locks and tags
• Bypassing procedures due to time pressure
• Poor communication between maintenance teams
• Failure to identify all energy sources (e.g. secondary hydraulic lines)

These failures highlight why the “Try Out” stage is so important, as it can identify problems before they lead to serious incidents.

Case studies

Case Study 1 – Contractor communication gap

Scenario:
A contractor performing maintenance on a chemical mixer assumed the plant operator had completed LOTO. The operator assumed the contractor had done it. The machine started unexpectedly, causing a severe injury.

Lesson learned:
Establish clear LOTO responsibility and communication when contractors are involved. Use a permit-to-work or sign-off system to ensure coordination.

Case Study 2 – Time pressure and shortcuts

Scenario:
During a production rush, workers bypassed LOTO procedures to clear a jam quickly. A worker’s hand was caught in moving parts, leading to amputation.

Lesson learned:
Reinforce a “safety over speed” culture. Management must not pressure employees to bypass safety procedures, and disciplinary policies should address intentional non-compliance.

Employer responsibilities

LOTO responsibility should be clearly established before any work commences, and procedures should be regularly reviewed and audited to ensure compliance.

Employers should ensure:

• clear isolation procedures are in place;
• employees and contractors are properly trained;
• all energy sources are identified;
• appropriate locks and tags are available;
• systems are in place to verify isolation before work begins.

Penalties for non-compliance

Businesses found violating health and safety laws may face:

• Improvement notices
• Fines
• Prosecution
• Compensation claims

Conclusion

LOTOTO is not optional — it is a legal and moral requirement for anyone working with machinery or hazardous energy.

By locking out, tagging out and trying out before work begins, organisations protect their workforce, comply with legislation and reduce the risk of catastrophic incidents.

A machine should never be assumed safe simply because it is switched off. Isolation must be verified. LOTOTO saves lives.

Explore AfterAthena’s health and safety services and get in touch today via our form. Whether you are looking for support on a one-off project or a full annual plan which has all corners covered, we have the depth of support for all organisations.

FAQs