EMC Directive FAQ Cables and wiring

Do not treat cable compliance as a standalone label question. First decide what is being supplied: a passive cable considered separately, a component or sub-assembly intended for incorporation by an end user, apparatus supplied with or specified for particular cables, or equipment incorporated into a fixed installation.

For apparatus, the manufacturer has to assess the relevant EMC phenomena in normal intended operating conditions and in the configurations it identifies as representative of intended use. If the apparatus only meets the essential requirements with a screened cable, a particular connector, a maximum cable length, a ferrite, a routing condition, or an earthing arrangement, those conditions belong in the EMC assessment, technical documentation, and instructions.

The practical split is whether the cable is merely a passive item considered separately or whether it is part of the apparatus configuration. The Directive treats certain components or sub-assemblies as apparatus when they are intended for incorporation into apparatus by the end user and are liable to generate electromagnetic disturbance or be affected by it.

If the manufacturer supplies the cable with the apparatus, requires a specified cable for compliant operation, or sells a cable/interface accessory that changes emissions or immunity, the compliance file should show how that configuration was assessed. Combining CE-marked products or accessories does not automatically prove that the resulting system is compliant.

Cable assumptions should be no broader than the evidence supports. The Commission guide says an EMC assessment has to cover normal intended operating conditions and, where apparatus can take different configurations, the representative configurations identified by the manufacturer. It also describes a documented worst-case approach for configurations likely to cause maximum disturbance or be most susceptible to disturbance.

For cables, that means the technical file should not silently rely on a laboratory setup that customers cannot reproduce. If a shielded cable, double-screened cable, specific external connection length, cable separation, equipotential earthing, or filter is needed, the instruction set should say so in clear installation language.

Fixed installations have a different compliance path from ordinary apparatus, but cables and wiring remain central to the evidence. The Directive requires fixed installations to meet the essential requirements and to be installed using good engineering practices while taking account of information on the intended use of the components that make up the installation.

Commission guidance gives cable examples for fixed installations: component instructions may concern the specified EMC environment, filters or other auxiliary devices, the specifications and length of external-connection cables, conditions for use, and special EMC precautions such as equipotential earthing. It also points to distances, earthing, cable selection, and screening as good-engineering-practice considerations.

The cable evidence should let a reviewer reconstruct the compliance argument without relying on project memory. Tie the cable facts to the apparatus model or fixed installation, the applicable essential requirements, the assessed configuration, and the instructions given to users or installers.

For apparatus, keep the technical documentation and EU declaration of conformity for 10 years after the apparatus is placed on the market. Importers must keep a copy of the EU declaration of conformity for the same period and ensure that technical documentation can be made available to authorities on request. For fixed installations, keep the good-engineering-practice documentation while the installation remains in operation.