An employee climbed a ladder to put the cover back on the motor of a high-speed overhead door. He needed to duck his head to get around the track to perform work on the motor. When third-party employees walked in front of the door on the opposite side, they triggered the motion sensor and the overhead door began to open. As the overhead door opened, it struck the injured employee in the left orbital socket and knocked him off the ladder. He fell six feet to the ground below and sustained a fracture to his forearm just below the elbow and a bruised left hip.