The injured employee went to help maintenance technicians install light fixtures on the ceiling. A maintenance tech then went down to grab a new fixture, as the injured employee went to climb a CNC machine. He placed one foot on the cable guide attached to the machine. His second step was on a nonstructural bar on the cabin that is used to mitigate warps. As he stepped on this bar, it fell down with him to the concrete floor. The employee sustained a broken right arm.