Types of energy in LOTO

Lockout Tagout (LOTO) is all about isolating all hazardous energy sources during maintenance — not just electricity. A common mistake is that technicians switch off the power and think the installation is safe, while mechanical, hydraulic or pneumatic energy can still be released. In this article we discuss the seven most important energy sources that you must isolate during LOTO or LOTOTO.

Which energy sources must be secured?

The LOTOTO procedure (Lock Out, Tag Out, Try Out) applies to all forms of energy that can cause injury or damage. Below you will find, per category, what you need to take into account — and which LOTO materials you need to lock them out.

Electrical energy

By far the most common energy source in industrial work. Think of:

  • Main switches
  • Distribution boards and miniature circuit breakers (MCB)
  • Batteries and UPS systems
  • Generators and solar panels

Lock out with an MCB lockout or safety padlock on the main switch. Don't forget to verify the absence of voltage with an approved meter — that is step 3 of NEN 3140.

Mechanical energy

Energy released by movement or stored force:

  • Moving machine parts
  • Springs under tension
  • Flywheels and rotating masses
  • Conveyor belts

Lock out with a hasp and padlock on the operating switch, and physically block movement if necessary with a wedge or pin.

Pneumatic energy

Pressure in air lines remains even after the compressor has been switched off:

  • Compressed air systems
  • Pneumatic cylinders
  • Compressors

Lock out valves with a cable lockout system and vent the system before you start work.

Hydraulic energy

Fluid under pressure can be released with enormous force:

  • Hydraulic pressure lines
  • Oil circuits in presses, cranes and machines

Close valves, lock them out, and release pressure in a controlled way before opening any lines.

Thermal energy

Heat or cold that can cause damage:

  • Steam lines
  • Hot water (central heating systems, boilers)
  • Furnaces and refrigeration installations

Always let installations cool down or warm up to ambient temperature first. Lock out the supply with shut-off valves and LOTO materials.

Chemical energy

Substances that are reactive, toxic or flammable:

  • Gases under pressure
  • Chemicals in process lines
  • Reaction pressure in vessels

In addition to LOTO, personal protective equipment (PPE) is also crucial here. Lock out supply valves and flush lines where necessary.

Potential energy

Energy stored through position or tension:

  • Suspended loads (cranes, hoisting installations)
  • Gravity — for example with lifts or upward mechanisms
  • Stored electrical charge in capacitors

Place suspended loads on a support, discharge capacitors, and block movement against gravity.

Try Out — the crucial verification step

Locking out all the above energy sources is step 1. Step 2 is verifying that the energy is really gone. Try to start the installation with the normal operating controls, and check with measuring equipment. Only then is your LOTO complete.

Which LOTO materials do you need?

For a complete LOTO set that can isolate all energy sources, choose:

Also take a look at our step-by-step LOTO procedure or the frequently asked questions for more explanation.