The electric power supply system is one of the most important research areas within sustainable and energy-efficient aviation for more- and especially all electric aircraft. This paper discusses the history in electrification, current trends with a broad overview of research activities, state of the art of electrification and an initial proposal for a short-range aircraft. It gives an overview of the mission profile, electrical sources, approaches for the electrical distribution system and the required electrical loads. Current research aspects and questions are discussed, including voltage levels, semiconductor technology, topologies and reliability. Because of the importance for safety possible circuit breakers for the proposed concept are also presented and compared, leading to a initial proposal. Additionally, a very broad review of literature and a state of the art discussion of the wiring harness is given, showing that this topic comes with a high number of aspects and requirements. Finally, the conclusion sums up the most important results and gives an outlook on important future research topics.