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  • Machine safety
- June 26, 2026

Modifications to Existing Machinery

Machines are regularly modified throughout their service life. Examples include increasing capacity, adding a new function, replacing a control system, or integrating a machine into a production line. Although such modifications are often technically feasible, they can also affect the machine’s legal status.

An important question in this regard is: Does the machine remain the same, or does the modification effectively create a new machine that requires a new conformity assessment and CE marking?

Not every modification has consequences

Many modifications do not affect the original CE marking. Examples include:

  • regular maintenance;
  • replacement of parts with equivalent parts;
  • repairs;
  • Minor modifications that do not affect safety or functionality.

In these cases, the original manufacturer remains responsible for the machine’s conformity, and the existing CE marking remains valid.

When is a modification considered significant?

A modification becomes critical when it creates new hazards or increases existing risks. According to the Dutch Labor Inspectorate, an assessment must always be conducted to determine whether the modification leads to:

  • new features;
  • higher speeds;
  • greater forces or loads;
  • changes to safety features;
  • new operating conditions;
  • other risks to users.

The assessment always begins with a risk assessment. This must determine whether the modification affects the machine’s safety.

Substantial modification

With the introduction of the Machinery Regulation (EU) 2023/1230, the concept of a “substantial modification” is explicitly defined in the legislation. A modification is considered substantial if, following the modification, the machine may no longer comply with the essential health and safety requirements that applied to the original machine.

Examples include:

  • adding an automatic function to a manually operated machine;
  • increasing a machine’s capacity or speed;
  • modifying safety control systems;
  • combining multiple machines into a single new system;
  • adding robotics or autonomous functions.

Who is responsible?

In the case of a major or substantial modification, the party carrying out the modification may be considered the manufacturer of the modified machine.

This means that Fedecom is responsible for:

  • conducting a new risk assessment;
  • preparing or updating the technical dossier;
  • demonstrating compliance with applicable legislation;
  • drafting a new EU declaration of conformity;

Reapplying a CE marking if required

This applies not only to machinery manufacturers but can also include end users, integrators, and technical service providers who modify machinery.

Guideline from the Dutch Labor Inspectorate

Because there are many questions in practice regarding machine modifications, the Dutch Labor Inspectorate has published a special Work Instruction on the Assessment of Modified Machines. This work instruction describes how to assess whether a modification affects the CE marking and what obligations arise from it.

The Labor Inspectorate emphasizes that the assessment must always be substantiated and documented. A well-documented risk assessment is essential in this regard.

Dutch Labor Inspectorate – Work Instruction for Assessing Modified Machinery

Machinery Regulation: Greater Clarity

During meetings of the Machinery Regulation Platform, the Dutch Labor Inspectorate explained that the new Machinery Regulation provides greater clarity regarding the concept of a “substantial modification.” This better defines when a modification results in new obligations for manufacturers. Work is also underway on an updated European guide for the application of the Machinery Regulation, which will explicitly address substantial modifications.

For companies that modify, modernize, or integrate machinery, it is therefore important to assess these changes not only from a technical perspective but also from a legal one.

Practical Considerations

Before modifying a machine, it is wise to answer the following questions:

  • Does the machine’s function change?
  • Do new risks arise?
  • Are existing risks increasing?
  • Are safety features being modified?
  • Is a new risk assessment needed?
  • Does the technical file need to be updated?
  • Does the modification affect the CE marking?

By answering these questions in advance, you can avoid unexpected obligations and liability risks.

Relevant sources:

Government

European regulations

Background Information