Frequently Asked Questions about Lockout Tagout (LOTO)

LOTO is the standard procedure to safely de-energize an installation during maintenance, repair or inspection — and to keep it that way. Lock Out means that you physically lock the main switch with a safety padlock. Tag Out means that you attach a warning tag (label) stating who is working on the installation and since when.

Within LOTO we speak of 'de-energized', while NEN 3140 speaks of 'voltage-free'. NEN 3140 is therefore about making voltage-free, while within LOTO other energy forms such as hydraulics, pneumatics, steam, pressure, kinetic energy, etc. are also considered.

The goal is simple: to prevent the installation from unexpectedly coming back into operation while work is being carried out on it. In most industrial sectors in the Netherlands, LOTO is mandatory under the Arbowet and NEN 3140 (in the electrical field). View our complete LOTO kits or the step-by-step LOTO procedure here.

LOTOTO stands for Lock Out, Tag Out, Try Out and is an extension of the classic LOTO procedure. The difference lies in that last step: after locking out (Lock Out) and labelling (Tag Out), you actively test whether the installation is really voltage-free by trying to switch it on (Try Out). Only when it turns out that the installation cannot start may you begin the work.

In the Netherlands, LOTOTO is increasingly seen as the minimum standard. The Try Out step has for several years been a recommendation within NEN 3140 and is regarded by the Inspectie SZW as best practice. For most lockout procedures you need the same products — LOTO padlocks, warning tags and possibly a lockbox for group work.

Yes, in virtually all industrial situations a lockout procedure is mandatory. The Arbowet obliges employers to protect employees against hazards during maintenance work on machines and installations. For electrical work, NEN 3140 specifically stipulates that installations must be voltage-free and demonstrably locked before work may be carried out on them.

Companies that do not comply run the risk of fines from the Inspectie SZW and — much more importantly — of serious accidents. LOTOTO is technically not a separate law, but is regarded by inspection services and industry organisations as the modern best practice.

Every time you carry out work on an installation in which stored energy may be present, such as electrical, hydraulic, pneumatic or, for example, mechanical or kinetic energy. Concrete examples are carrying out maintenance on switchboards, repairing conveyor belts, inspecting pumps, replacing electric motors, work in data centres, cleaning work on machines that could be started by accident.

In general, you can state that if the installation could accidentally come back into operation during your work and thereby pose a danger, then you apply LOTO. In doubt? Then the answer is always: yes, lock out.

With LOTO(TO) we look not only at electrical energy, but also at other forms of stored energy. The most important types are:

• Electrical energy: Think of mains power, batteries and capacitors.
• Mechanical energy: Moving parts such as motors, flywheels, shafts, gears and springs.
• Pneumatic energy: Air pressure or vacuum in cylinders and lines.
• Hydraulic energy: Fluid pressure.
• Thermal energy: Heat or steam from, for example, furnaces, hot pipes or cooling systems.
• Gravity (potential energy): Suspended, raised or heavy parts that can fall down.
• Chemical energy: Hazardous substances, gases and acids.

Both standards prescribe how to work safely on electrical installations, but apply in different countries. NEN 3140 is the Dutch standard for the operation of low-voltage installations and is valid in the Netherlands. OSHA 1910.147 is the American federal standard for lockout/tagout and there it is mandatory.

In practice they overlap strongly: both require locking, identification and verification. Products that comply with OSHA usually also comply with NEN 3140. Our entire LOTO catalogue is compliant with both standards.

A complete LOTO set contains everything a technician needs for a safe lockout procedure: several safety padlocks with unique keys, padlock multipliers (hasps) for situations with several technicians, lockout systems for circuit breakers (MCB lockout), 'Do Not Operate' warning tags, and possibly cable lockouts for shut-off valves and non-standard switches.

For maintenance teams on site, you often choose a portable LOTO kit or a wall station. View our LOTO Kits or the Lockout Stations.

Nylon padlocks are non-conductive — ideal for electrical work and on switchboards where contact with live parts is possible. They are light, corrosion-resistant and suitable for most industrial environments. They are also slightly cheaper than metal locks.

Metal padlocks are physically more robust and resistant to harsh conditions — think of heavy industry, outdoor work or places where the lock may be physically attacked. Our metal LOTO locks have an insulated shackle, so that they also remain safe during electrical work.

The 38mm shackle is the standard and fits most industrial switches, main breakers and padlock multipliers. For 90% of LOTO applications, 38mm is sufficient.

You choose the 76mm shackle when you have lockout points that a short shackle cannot fit around — for example larger valves, thick switch handles, main switches in older installations. In doubt? Start with 38mm and keep a few 76mm locks on hand for exceptions.

A lockbox is a safety box that you use when several technicians work on the same installation at the same time, but there is only one common switch. The key of the lockout lock on that switch goes into the lockbox, and each technician places their own LOTO padlock on the box.

The installation can only be put back into operation when everyone has removed their lock. Indispensable for major maintenance shutdowns, shift handovers and project work. View our Lockboxes.

A lockbox is used in LOTO to store the keys of locked systems, so that machines are not accidentally switched on during maintenance or other work. A commonly used procedure is as follows:

1. Switch off and lock out: The installation is made safe and the main switch or shut-off valves are locked with LOTO safety padlocks and provided with a label (Tag).
2. Keys in the lockbox: The keys of all participating parties go into the lockbox.
3. Personal padlock on the lockbox: Everyone on the team then places their personal padlock and label on the lockbox.
4. After completion of the work: The installation can be started up again after all personal safety locks have been removed from the lockbox and the box can be opened to access the keys and remove the padlocks.

LOTO padlocks are deliberately supplied in striking colours so that a locked installation is recognisable from a distance. Red is by far the most used colour and has the clearest 'danger / do not operate' association.

Yellow is often used to distinguish between disciplines (for example: red for electrical engineering, yellow for mechanical engineering) or between shifts. We carry both colours in our LOTO Padlocks collection.

Different colours of locks are often used for different groups of people, such as contractors, E&I or Persons in charge of work, etc.

Only an authorised person may perform a lockout, that is, someone who has been trained for it and who understands the risks of the work and the installation. For electrical work according to NEN 3140 this means: a Sufficiently Instructed Person (VOP) or a Competent Person (VP), depending on the complexity of the installation.

In practice: technicians, electricians, maintenance technicians and operators who have been designated for this by the employer. Without the right instruction, you may not carry out a LOTO procedure.

This happens regularly and is exactly why the procedure is set up so strictly. Most important rule: never simply cut off a colleague's lock. It may be that he or she is still working on the installation, or has just stepped away.

Follow your organisation's escalation procedure: first try to reach the owner; if that fails, involve the supervisor or safety officer; only when it is demonstrably certain that the installation is safe may the lock be removed, usually by two authorised persons together, with written documentation.