EMC Information

General Information

In electrical/electronic engineering, enclosures assume two tasks:

  • protection of the installed components from mechanical hazards and adverse radiation from outside
  • protection of the surroundings from occurring mechanical and electrical hazards and adverse interference radiation from the components installed

Especially the electromagnetic compatibility (EMC) has an increasing effect on the selection of enclosures because of the ongoing development of the electronic components and the increased equipment density on the PCB’s – which increasingly generates “pollution” by electromagnetic interference radiation in the environment.

Legal Regulations

Within the framework of harmonising the European standards, an EC guideline directive (05.89/336/EEC) was passed in May 1989, which took effect in the Federal Republic of Germany on the 9th Nov. 1992 in the EMC law (EMVG).

This law is applicable to all units which might cause electromagnetic interference or the operation of which could be impaired by such interference.

The EMC directive came into effect on 1.1.1996 EC-wide – from which date all new electrical and electronic units brought into circulation within the EC had to fulfil these regulations.

As an external sign that the EC relevant laws (EMC law and further design basics), these units have to show the CE symbol.

Requirements From the Enclosure

Enclosures as such are not subjected to the EMC law, as by definition they are not electrical or electronic units. However, enclosures are to a large extent responsible for the intensity of interference emission (receipt and transmission of interference waves) of a unit. At this point, the choice of the enclosure material is also decisive for the screening effect which is composed of a reflection and an absorption damping of a enclosure.

Synthetic materials (plastics) alone have no filtering effect on interference radiation. A screening effect can be achieved by additional costly treatment (metal flashing or application of a conductive lacquer).

Metal enclosures , on the other hand, offer a highly effective basic protection against interference radiation. (Here an important factor is a large contact surface of the individual components of the enclosure (cover, enclosure shells).

To meet special protection requirements, the EMC compatibility can be increased by

  • conductive seals
  • contact bare front surfaces as well as
  • EMC compatible cable screw connections