Substantial modification

A change to a machine that was not foreseen and may affect safety. Whoever makes it takes on the duties of a manufacturer under the Machinery Regulation.

Under the Machinery Regulation (EU) 2023/1230, a substantial modification exists when machinery or a related product is changed after being placed on the market in a way the manufacturer did not foresee and that affects safety by creating a new hazard or increasing an existing risk. The change can be physical or digital, so a software update can qualify. What counts is whether new protective measures become necessary, such as additional guards or an intervention in the safety control system. According to the recitals of the Regulation, repair and maintenance that do not affect compliance with the safety requirements are not substantial modifications. The Regulation applies from January 20, 2027, and replaces Machinery Directive 2006/42/EC.

The consequence is in Article 18: whoever carries out the substantial modification is considered the manufacturer. That person must carry out a risk assessment, apply the relevant conformity assessment procedure and declare on their own responsibility that the machinery meets the requirements. That can be a service company doing the conversion, but also the operator itself. The Product Liability Directive (EU) 2024/2853 works similarly in Article 8(2): anyone who substantially modifies a product outside the manufacturer's control and then puts it into service is considered the manufacturer of that product.

Do not confuse substantial modification with a modification that requires an inspection under § 2(9) BetrSichV. That concept is broader: any measure that affects the safety of work equipment can count, even a repair. The consequence there is an inspection before the next use (§ 14(3)), and for installations subject to monitoring before recommissioning (§ 15). A change can therefore require an inspection without being substantial in the sense of product law. For cost, this means a conversion quote should state who takes on the conformity assessment and who pays for the inspection.

What matters

• Have every conversion, retrofit and software update to a safety function assessed in advance, and record the result in writing.
• In the quote, ask the service company whether it sees a substantial modification and who then takes on the manufacturer's duties.
• Check with the manufacturer whether the change was foreseen by it.
• File the new declaration of conformity, risk assessment and inspection report in the asset file.
• Schedule the inspection after a modification that requires one before the installation runs again.

In the original wording

Related regulations

In vi

• Asset file: One asset, one file