||Rapidly increasing usage of telecommunication systems causes new transmission technologies and networks to emerge. Not only the efficiency, reliability and accessibility of the network are important, but also the economic issues. One cost-effective solution could be power line communication (PLC) technology, which transmits data using the existing electricity infrastructure. The application of this communication technique is an attractive and innovative solution for the realization of smart cities and smart homes. With intelligent control networks, energy savings can be optimized and the operating as well as maintenance costs can be reduced. Since outdoor lighting systems are the major consumers of electricity, to create a modern, energy-efficient city, intelligent street lighting control is needed. This paper provides an overview of power line communication principles including the theoretical background of data communication, modulation techniques, channel access methods, protocols, disturbances and noises. Furthermore, in order to highlight the benefits of a PLC-based street lighting control system, a pilot project will be presented.