In the case of a system assembled from only CE marked apparatus put together by the same person (the system manufacturer) and placed on the market as a single functional unit, the system manufacturer assumes responsibility for compliance of the system as a whole with the Directive. In this case the EC declaration of conformity (made by the system manufacturer) as well as the instructions for use must refer to the system as a whole. It must be clear (eg by enclosing a list of all parts) which is/are the combination(s) that form the system placed on the market for distribution and/or for use. The system as a whole does not need to bear the CE marking. The system manufacturer assumes responsibility for compliance with the Directive and must therefore provide clear instruction for assembly/installation/operation/maintenance in the instructions for use.

Manufacturers of systems assembled from only CE marked apparatus should be aware that combining two or more CE market subassemblies may not automatically produce a system which meets the requirements of the relevant standard. Eg a combination of CE marked PLCs (Programmable Logic Controller) and motor drives within a machine tool together to be placed on the market as a system may fail the requirements, whereas a HI-FI system composed of separatly CE marked amplifier tuner, CD player and Cassette deck wired up correctly is quite likely to maintain its compliance.