When do you use different colours of safety locks?

Colours play an important role in lockout tagout (LOTO) procedures. A coloured safety lock is not only eye-catching — at a glance it communicates who has locked out the installation, why, and which rules apply to its removal. In this article we explain when to use which colour of LOTO padlock, and how to set up a colour-coding system for your organisation.

Why different colours in LOTO?

An installation can be locked out simultaneously by several disciplines, shifts or external parties. Without colour-coding, everything looks like 'someone is working on it' — but you don't know who, or how many people. Colour-coding solves this through immediate visual distinction:

  • Quick identification — immediately see which group or discipline is at work
  • Accountability — clear who is responsible for which lock
  • Safety culture — colours make procedures visible and open to discussion on the shop floor
  • Compliance with NEN 3140 and Arbowet (Dutch OSH legislation) — unambiguous communication is a legal principle

The most commonly used colours and their application

There is no legal standard for LOTO colour-coding, but in Dutch and international industry these conventions are common:

Red — the standard

The red LOTO padlock is by far the most widely used. Universally recognised as 'danger / do not operate'. Ideal for general LOTO applications by in-house technicians.

Yellow — distinction between disciplines or shifts

The yellow LOTO padlock is often used to distinguish, for example, electrical engineering (red) from mechanical engineering (yellow). Also handy for shift handovers or a second team of technicians.

Blue — for contractors or external parties

Blue padlocks are used for maintenance parties from outside the company, so it is clear when an external party is working on the installation.

Green — for inspection or trainees

Green locks are often reserved for inspectors or trainees who only observe or measure, rather than actively carrying out work.

Orange, purple, black — company-specific

For larger organisations with multiple departments, sites or disciplines, additional colours are often introduced. Important: record the meaning in an internal document so that everyone follows the same convention.

How do you set up colour-coding?

  1. Take stock of your disciplines and groups — which departments work on installations? Who are the external contractors?
  2. Assign colours to groups — use common conventions where possible (red = standard, yellow = distinction)
  3. Document it in a work instruction — so that newcomers and external parties know what each colour means
  4. Train your employees — link colour to procedure in toolbox meetings
  5. Keep stock per colour — make sure the right locks are available on the shop floor

Combining with personal identification

In addition to colour-coding, you can identify individual technicians via a personally engraved number or a name label on the lock. This way you see not only which discipline is working on the installation, but also which person is responsible.

View our coloured LOTO padlocks

LockOutStore.nl stocks LOTO safety padlocks in both red and yellow, in nylon and metal, in 38mm and 76mm shackle height. All locks comply with NEN 3140 and the Arbowet and are available directly from stock. For other colours or larger quantities: request a no-obligation quote.