The pilot decided to inspect a nearby private landing strip which was sometimes used by ultralight pilots. Prior to departure he had obtained details about the strip, which included some information on powerlines in its immediate vicinity. Upon arrival, the pilot carried out both an area, and a strip inspection to identify the hazards. He then descended to about 25 feet to carry out an inspection of the surface of the strip. About half way along the strip the aircraft struck a powerline and impacted the ground inverted. The pilot extricated himself from the wreckage just before the aircraft was consumed by fire. The area assumed by the pilot to be a strip, was in fact an access taxiway to the strip which was bisected by a powerline. During the high level observation, the pilot satisfied himself that he had identified the powerlines, however, the subject powerline escaped his attention. Although he obtained some information on the strip before departing, the pilot did not seek a detailed briefing considered necessary for flight at such a low height above an unfamiliar area.