Electromagnetic compatibility - EMC

The emissions from electrical devices and equipment and their immunity to disturbances must comply with the requirements. All electrical devices and equipment affect each other when they are in close proximity or connected. The purpose of electromagnetic compatibility (EMC) is to ensure that electrical devices or equipment do not create disturbances that would affect other devices or equipment and are immune to disturbances caused by them.

The manufacturer of the electrical device or equipment is responsible for ensuring that the device or equipment is compliant with the requirements of the EMC Directive. Electromagnetic compatibility is regulated by the Electrical Safety Act and the EMC Directive.

What is an EMC disturbance?

Disturbances in electrical devices or equipment include all electromagnetic phenomena not intended for practical use. Disturbances spread from equipment or a device to other equipment or devices either through cables or via radiation. For example, lines in a television picture, static on the radio or computer malfunctions are often due to disturbances caused by other electrical devices or equipment.

Scope of application

The EMC Directive applies to all electrical devices or equipment that may cause electromagnetic disturbances or whose functioning may be affected by electromagnetic disturbances.

The EMC Directive does not apply to

  • radio equipment
  • aeronautical products
  • radio equipment used by radio amateurs
  • Custom-built evaluation kits destined for professionals to be used at research and development facilities
  • installations or equipment which are inherently benign in terms of electromagnetic compatibility.

Examples of EMC passive electrical appliances:

  • Appliances containing only resistive loads without electronics (simple heaters without temperature control, thermostat or fan)
  • Batteries and accumulators (without active electronic circuits)
  • Passive speakers
  • Flashlights without active electronic circuits  
  • High voltage inductors and transformers
  • Induction motors without electronic circuits Quartz watches (without additional functions such as a radio receiver) 
  • Home and building switches which do not contain any active electronic components 
  • Connectors, plugs, cable terminals, etc.

If the EMC requirements of electrical devices or equipment are provided for in another legislation in whole or in part, the EMC Directive shall not apply in that respect. For example, the EMC Directive does not apply at all to:

  • Radio equipment (the Radio Equipment Directive refers to the essential requirements of the EMC Directive)
  • Medical devices
  • Vehicles and their equipment
  • Vehicles with 2–3 wheels
  • Marine equipment
  • Agricultural and forestry tractors

The EMC Directive partially applies to measuring instruments and non-automatic weighing instruments. In these cases, the emission requirements are laid down in the EMC Directive, and the immunity requirements in special legislation. There are stricter immunity requirements for these product groups, because their measuring result determines the price of the product or substance to be measured.

Impact of operating environment on EMC requirements

The legislation includes only essential requirements concerning electromagnetic compatibility and labelling requirements for electrical products. The standards lay down the limit values for immunity and emissions requirements. The limit values take into account the intended operating environment of the product, i.e. whether its intended use is in a residential area or in industry, for example. In an industrial environment, the limit values for emissions are somewhat higher than in a residential area, but correspondingly, the appliance must endure more disturbances. 

If the product is not intended for use in a residential area, a clear indication of such restriction of use must be included with the product and also on the packaging, where appropriate. The consumer must know about the restriction before making the purchase decision.

The descriptions used in harmonised standards (for example “this is a class  A product”) are not suitable without further explanation, as they are not understood by the general public. You could mark a restriction as follows:

  • This product must not be used in residential areas.
  • This product may cause interference if used in residential areas. Use in the residential area must be avoided unless the user takes special measures to reduce electromagnetic emissions to prevent interference.

Issues to consider in EMC assessment

The EMC assessment must consider not only the operating environment, but all normal operating methods of the electrical product. For example, if the product can be used and charged at the same time, the product must be tested according to the “worst case scenario”, i.e. when the appliance is charged and used at the same time.

The EMC requirements apply to the whole set of equipment that is commercially available. The entity can be a combination of several equipment. The combination of two or more CE marked equipment does not automatically produce a compliant entity. Instead, the conformity of the combination of equipment must always be assessed separately.

In cases where the electrical product might be included in different assemblies, the electromagnetic compatibility assessment ensures that the product meets the requirements in all possible assemblies. In this case too, the “worst case scenario”, i.e. the assembly with all the accessories/features, is tested. The manufacturer is responsible for identifying possible assemblies and choosing the worst-case scenario.

How to ensure the conformity of electrical devices

Obligations of the manufacturer, importer and seller

In addition to product requirements, the EMC Directive creates a number of obligations for the manufacturer, importer and seller of the product.

How to ensure the conformity of electrical equipment

The EMC Directive includes different regulations on electrical equipment from those on electrical devices, because electrical equipment cannot move freely within the European Union.

The manufacturer of electrical equipment must design and build the equipment in accordance with good engineering practices so that when maintained and repaired correctly, the electrical equipment is electromagnetically compatible. Electromagnetic compatibility means that the installation fulfils the essential requirements of the EMC Directive concerning electromagnetic compatibility as well as the specific requirements for fixed installations.

The manufacturer of the electrical equipment must document the engineering practices applied and hand the documentation over to the possessor of the electrical equipment.

An electrical device incorporated in a specific fixed installation

If an electrical device is incorporated in a specific fixed installation and is not available for sale otherwise, the manufacturer of the device does not need to carry out a conformity assessment procedure on the device in accordance with the EMC Directive. However, the product may not compromise the EMC characteristics of the fixed installation. The manufacturer does not need to draw up an EU Declaration of Conformity for the device or affix a CE marking.

In the documentation of the electrical device, the manufacturer must

  • identify the fixed installation in question
  • indicate the precautions to be taken for the incorporation of the device into the fixed installation in order not to compromise the conformity of that installation
  • provide the information and markings required by the EMC Directive.

Frequently asked questions