Abstract: On August 26, 2008, an employee and a coworker of an electrical subcontractor were cutting holes through a 16-in. thick, poured concrete wall with a core drill. They were working on a fabricated work platform comprised of wooden planking placed between two 12-ft, composite stepladders at a height of between 10.5-ft and 11-ft above the floor. The rig for the core drill was supported on a threaded bolt inserted in the wall above the drill site. When the third of four holes was completed, the employee loosened the nut on the support bolt to reposition the core drill. The nut came off of the bolt and base plate of the drill rig slid off the bolt. The weight of the drill and drill rig caused the employee to fall backwards off of the plank. The employee landed on a piece of exposed, uncapped, Number 6-gauge steel rebar protruding from the wall of a partially-constructed stair landing located adjacent to the work platform. The rebar entered the employee's left side below the arm pit, passed through the upper torso and exited his right side and right arm. The employee was hospitalized and treated for puncture wound.