When does a linked line need CE marking for the installation as a whole?
One CE marking for the whole installation is required when all four criteria of the German interpretation paper are met at the same time: spatial connection, connection in terms of process and function, an overarching control system, and a single safety unit. If even one of them is missing, the linking is minor and the individual machines keep their own CE marking.
Which four criteria have to be met?
All four criteria have to be present at the same time. That is the decisive point where most misjudgements arise.
Does a shared emergency stop already create an assembly?
A shared emergency stop circuit across several machines is expressly not a sufficient condition under the interpretation paper. On its own it constitutes minor linking. The individual machines keep their own CE marking and no new overall machine comes into being.
The misunderstanding is widespread because the shared emergency stop is perceived as the most visible sign of a connection. What matters, though, is whether an overarching control system coordinates the process and whether safety technology merges into a single unit across machine boundaries.
How do I assess this for my installation?
What does this mean for a typical conveyor line?
Example: a palletiser, a strapping machine and a stretch wrapper connected by roller conveyors. Each machine carries its own CE marking.
Variant A, minor linking: each machine runs with its own control system, the goods are merely passed on, and there is only a shared emergency stop. The individual CE markings remain. The operating company assesses the transfer points as part of its workplace risk assessment.
Variant B, assembly: an overarching PLC synchronises the three machines, guard doors at the strapping machine also stop the palletiser, and the safeguards are wired into a common safety concept with zones. All four criteria are then met: a new overall machine comes into being, with its own risk assessment, its own instructions for use and its own declaration of conformity.
The difference between the two variants is not a question of the size of the installation but of the control and safety architecture.
Do the individual machines keep their own CE marking?
The CE marking of the individual machines does not become invalid through an overall CE marking and does not have to be removed. It continues to relate to each machine within its own scope of supply.
The overall declaration of conformity comes in addition and covers the installation as a functional unit, in particular everything that only arises through the linking: transfer points, shared access areas, the overarching safety concept and the interactions between the machines.
The documentation of the individual machines becomes part of the technical documentation of the whole installation. The manufacturer of the assembly may rely on the conformity of the individual machines but has to assess the interfaces itself.
Sources and standards
- Interpretation paper on assemblies of machinery (BMAS, BAuA, DGUV, VDMA, 2011)
- Machinery Regulation (EU) 2023/1230
- Machinery Directive 2006/42/EC (valid until 19 January 2027)
- EN ISO 12100: risk assessment and risk reduction
Editions of standards and their harmonised status change continuously. Check standard numbers and editions against the current list in the Official Journal of the EU before applying them. This article is a technical classification and does not replace legal advice.
Frequently asked questions
Who becomes the manufacturer of an assembly of machinery?
Whoever connects the individual machines into a functional unit and places the installation on the market or puts it into service. Usually the system integrator or main contractor, otherwise the operating company.
Is a data link to the warehouse management system enough as an overarching control system?
No. What is meant is a control level that coordinates the sequence of the individual machines. A mere exchange of orders or data with an ERP or warehouse management system does not meet the criterion.
Does the interpretation paper still apply under the Machinery Regulation from 2027?
The 2011 paper relates to Machinery Directive 2006/42/EC. Its logic for drawing the line remains the technical reference in the German-speaking area. Before the deadline, check whether an updated version or supplementary guidance on the Machinery Regulation exists.
What happens if I overlook the assembly?
Then neither a risk assessment nor a declaration of conformity exists for the installation as a unit. Precisely those hazards that only arise through the linking are then unassessed, typically at transfer points and shared access areas.
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This article was produced with AI assistance and reviewed for technical accuracy before publication. Editorial responsibility within the meaning of Art. 50(4) of the AI Act (EU) 2024/1689 lies with Heinrich Knutas.
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