The interpretation paper on the subject of "Substantial modification of machinery" from the Federal Ministry of Labour and Social Affairs (BMAS notification dated 09.04.2015 - IIIb5-39607-3 - in GMBl 2015, No. 10, pp. 183-186) states the following:

Any modification to a machine, whether used or new, which may affect the protection of the legal interests of the ProdSG, e.g. by increasing performance, changing functions, changing the intended use (such as by changing the auxiliary, operating and input materials, conversion or changes to the safety technology), must first be examined with regard to its safety-relevant effect. This means that it must be determined in each individual case whether new hazards have arisen as a result of the change in the (used) machine or whether an already existing risk has increased. Three different cases can be distinguished:
1. there is no new hazard or no increase in an existing risk, so that the machine can still be considered safe.
2. there is a new hazard or an increase in an existing risk, but the existing protective measures of the machine before the change are still sufficient for this, so that the machine can still be considered safe.
3. there is a new hazard or an increase in an existing risk and the existing protective measures are not sufficient or suitable for this.
Additional protective measures are not required for modified machinery according to case design 1 or 2. Modified machinery according to case design 3, on the other hand, must be systematically investigated further by means of a risk assessment with regard to the question of whether a significant change has occurred.

If the above-mentioned 3rd case applies, it must be checked whether the machine can be brought back into a safe condition with simple protective devices. These are, for example, fixed guards, or movable guards and non-separating guards that do not significantly interfere with the existing safety-related control system.

If components with identical functions are replaced, e.g. when the control system is replaced, the safety-related properties must be at least equivalent to those of the existing system. If this is the case, there is no increased or new risk and the modification is not considered a significant change. A closer look must be taken at the replacement of components if new components have worse safety-related properties than the original parts.

If, in the course of the assessment, it is determined that the modification to the machine is not a substantial modification, the machine must continue to meet all the health and safety requirements that existed when the machine was first placed on the market. If, after assessing the modification, it is concluded that it is a substantial modification, the machine must be considered as a new machine in the sense of the MRL and a new CE conformity assessment procedure must be carried out.

Decision chart:

Example: Conversion from manual loading to automatic loading by means of a robot1

  1.     Is there a new hazard? Yes, due to movement of the robot.
  2.     Does the new hazard lead to a risk? Yes, there are possible crushing or shearing points.
  3.     Are the existing protective measures sufficient? No, the robot would be freely accessible.
  4.     Can the risk be eliminated or sufficiently minimised with simple protective devices? Carry out a risk assessment. Possible output for the example: Yes, the risk can be sufficiently reduced by erecting a movable guard and integrating it into an existing safety function/deactivating a safety function of the existing machine.
  5.     No significant change


In the case of robots, it is important to note that they are usually partly completed machines. For implementation, this must have a CE marking.

These decision-making steps must be carried out separately for each new risk.

We will be happy to assist you both in assessing the change and in any further steps.