What is Lock-out Tag-out (LOTO)?
Lock-out Tag-out (LOTO) is a safety procedure that ensures machines and installations are safely de-energised before maintenance or repair work begins. LOTO prevents energy (electrical, mechanical, hydraulic, etc.) from being inadvertently re-applied, helping to prevent serious injury or damage.
LOTO is mandatory in many industrial environments under the Dutch Working Conditions Act, NEN 3140 and international safety standards such as ISO 45001 and OSHA 1910.147.
🧠 How does Lock-out Tag-out work?
- Preparation
- Identify all energy sources of the installation
- Inform those involved (operators, technicians)
- Shutdown and isolation
- Switch off power via the main switch, fuse, valve or tap
- Bring energy to zero: electrical, pneumatic, hydraulic, thermal
- Lock-out
- Physically lock the energy source with a padlock
- Only the responsible technician holds the key
- Tag-out
- Attach a warning label (who, what, when, why)
- Clearly indicate that the installation must not be switched on
- Verification and testing
- Verify that no energy is present (measurement, pressure check)
- Perform a trial start (if applicable)
- Re-energising
- Once work is finished: lock and tag are removed by the original user
- Inform those involved and restart according to procedure
Each lock-out point must be included in a LOTO plan or work instruction.
🏭 Application in industrial environments
- Maintenance on control cabinets, MCCs, PLCs, motor starters
- Replacing sensors, actuators, pumps, motors
- Installation work, inspections, cleaning
- Working near moving parts or electrical circuits
Typical sites:
- Chemical plants, food industry, logistics, power stations
- Used in conjunction with work permits, NEN 3140, Incident Management
🔍 LOTO vs. other safety measures
| Measure | What does it do? | Level of control |
|---|---|---|
| LOTO | Prevents inadvertent re-energising | Technical and organisational |
| Emergency stop | Stops the installation in an emergency | Operational |
| Access system | Manages who has access to where | Preventive |
| Work permit | Authorisation and oversight of activities | Organisational |
🔐 Safety considerations
- Physical locking of energy points
- Personal LOTO padlocks → each employee has their own key
- No restart possible without proper authorisation
- Mandatory education and training for technicians (in line with NEN 3140)
- Documentation of procedures and risk assessment
Errors in LOTO can lead to serious injury or fatal accidents.
📌 In summary
Lock-out Tag-out is a critical safety procedure that allows maintenance on industrial installations to be carried out de-energised and free of risk. It combines physical locking with clear signage to prevent human error and energy-related hazards.