Abstract: Two power line workers were replacing a No. 4 AWG aluminum triplex service cable with a larger No. 2 AWG cable. The two employees had inspected the existing installation before beginning work. The existing cable had been attached to the house for a number of years and was a length of about 41 meters from the mid-span connection to the weatherhead on the house. As the employees were stringing the new cable, the service knob, which was attached by a 76-millimeter-long screw to the fascia board on the house, gave way and snapped back toward one of the employees, an apprentice, who was standing on a 6.1-meter-tall stepladder about to connect his body belt to the ladder's D ring. The apprentice lost his balance and fell to the ground, a distance of about 4 meters. He suffered a serious injury to his pelvis and wrist and was hospitalized for his injuries.