The pilot of the glider stated that he was returning to the airport at the conclusion of a one-and-a-half hour flight, and approached the airport at a low altitude and slow airspeed. The pilot continued the approach for landing, and struck a telephone wire on the final leg of the traffic pattern. The glider sustained substantial damage to the wing spar and tail boom. The pilot reported there were no mechanical malfunctions or anomalies with the glider.