CARLISLE CONTRACT HAULAGE DRIVER DROVE UNDER 13.8 KV POWER LINES WITH BED IN RAISED POSITION. PULLED AND BROKE BOTTOME PHASE OF LINE. INCIDENT OCCURED AT PROCESS PLANT SCALE LOCATION. NO INJUR Y, NO DAMAGE TO TRUCK. POWER DISRUPTED AT MINE FOR APPROX. TWO HOURS. LINE LOCATED APPROX 25 FOOT ABOVE GROUND, OVERHEAD LINE WARNING SIGNS IN AREA.