Electric and electronic equipment is always transmitting electromagnetic interference that can disturb other equipment or systems. These disturbances can be slight, momentary functional disorders but they can also lead to functional disability or even to destruction of the equipment.

In 1989 the directive 89/336/EEC for regulations concerning electromagnetic compatibility (EMC directive) was adopted to introduce protective measures against this problem. Through this directive the safe and reliable operation of electronic equipment is insured by protecting it from interference from other equipment as well as defining interference levels under which the equipment must still operate reliably. As all other directives, this directive does not stipulate specific limit values but defines the principal protection requirements, i.e. the essential requirements.

According to article 10 of the EMC directive,
three conformity assessment procedures are specified: