Abstract: At approximately 10:50 a.m. on April 10, 2012, Employee #1, a first step electrical Apprentice was traveling across the top portion of a high-voltage tower cage that was staged in the horizontal position on the ground. Immediately before the first tower segment was being lifted into position, while Employee #1 was travelling point to point to complete the ground assembly work, a work crew was in the process of connecting the crane rigging on each end of the main rails, to lift the tower cage to the vertical position. The crew had finished assembly on the ground; Employee #1 was on top of the cage and had just finished hooking up the cage to the crane operated by a coworker. Employee #1 had been instructed to tighten up the few remaining bolts. Employee #1 was moving from the west side main rail to the east side main rail, crawling across a horizontal member that was 5 inches wide and 15.75 feet long. E1's right hand slipped or wobbled, causing him to lose his balance while crawling across a horizontal member on a tower cage lying on its side, Employee #1 "barrel-rolled" around the beam and then fell off. Employee #1 fell about sixteen-feet to the ground to soft bare ground, landing on his chest, face and abdomen. Employee #1 was transported via ambulance to LA County-USC Medical Center for evaluation and treatment. He was in hospital for seven days, treated for an eye socket fracture and a lacerated kidney. Employee #1 was wearing work positioning equipment at the time of the accident but was travelling point to point and was not connected to a structural member. Employee #1 has been trained by Employer in fall protection and heat illness prevention in late October 2011, when he first began to work on this construction project. The Employer is a construction company that specializes in high-voltage tower construction. The worksite was an isolated hilltop in open country on top of a ridgeline.