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§ Article 3(16) · articles 17 and 18
Six questions, in the order the text puts them. At the end, a reasoned verdict — and the assessment sheet to print and sign. That sheet is what counts: you do not become a manufacturer by modifying a machine, you become one by modifying it without writing it down.
§ Why these three criteria
Article 3(16) defines substantial modification through three conditions that must be met together. Article 18 draws the consequence: whoever carries it out is considered the manufacturer of the modified machine.
Criterion 1Not foreseen
The modification is carried out after placing on the market, by physical or digital means, and was not foreseen or planned by the manufacturer. An adjustment described in the instructions, a catalogue option, a kit sold by the maker: all of that was foreseen, and falls outside.
Criterion 2Safety
It creates a new hazard or increases an existing risk. A modification that improves safety without creating another risk, or that touches neither function, nor throughput, nor energies, does not meet this criterion.
Criterion 3Safeguards
It makes it necessary to add or change protective measures: a guard, a protective device, or a rework of the safety logic. If the existing measures cover the new situation without being touched, the criterion is not met.
Three yeses: you are the manufacturer of the modified machine. One single no: you are not — but you must be able to show it.
Source: Regulation (EU) 2023/1230, article 3(16) (definition), article 17 (placing on the market under one's own name) and article 18 (obligations in the event of substantial modification) — EUR-Lex. See also our guide to the Regulation.