Abstract
After reviewing some basics of dielectric withstand of air insulation, we introduce two procedures for an improved prediction of streamer paths in complex geometries. Although based on the electric background field, we generalize conventional models that usually consider paths starting at a field maximum and traveling along field lines. The new approaches are able to explain both streamer inception points different from field maxima as well as deviations of the streamer path from field lines, and may help to further optimize dielectric withstand of high voltage devices.