Prior to the flight the pilot was given details of the paddock in which the glider was located, by the glider pilot. This information included reference to power lines on the western side. An inspection run into the west was performed at 300 feet agl and as a run at a low height towards the east was commenced the landing gear struck a power line suspended 9 metres above the ground. The aircraft struck the ground in a vertical nose down attitude and came to rest inverted. The power line ran obliquely across the paddock from a line of poles paralleling a railway track. There were no supporting poles in the paddock to alert the pilot as to the whereabouts of a power line and he assumed that those running next to the railway were the ones mentioned in the briefing.