In this paper, we give an overview of the experimental and theoretical PLC- related research work carried out in close cooperation by the Swiss Federal Institute of Technology and the University Of Applied Sciences Of Western Switzerland. The work is conducted in the framework of the OPERA project and of a research contract with OFCOM. It is the EMC aspects of data transmission over power cables that are essentially are covered in this research. Much of the effort is dedicated to the experimental and theoretical characterization of conducted and radiated emissions from poorly symmetrical cables in the LV and MV networks. Our investigations focus in part on the evaluation and possible improvement of the k factor concept. For both, the radiation and the conducted emissions problems, a key issue studied is the common/differential mode conversion phenomena in the lines. Other work includes the study of emissions mitigation techniques and immunity test methods