Abstract: At approximately 11:04 a.m. on June 7, 2012, an electrician at a work site in San Francisco, CA, was facing the northeast direction with the power disconnect of a tower crane in front of him. He was kneeling down while working on the balonga cords of the power disconnect. A 46mm socket and extension fell from the crane and struck him in the back, near the right shoulder blade. He was evaluated by the onsite first aid personnel. He refused treatment from the San Francisco Fire Department. At the time, he was able to rotate his right arm 360 degrees with discomfort. The following day, June 8, 2012, the employee was not feeling well. He called into work and was told to go to an urgent care facility. He was admitted to St. Francis Memorial Hospital and treated for broken ribs and a punctured lung. The accident was reported to the San Francisco District Office of Cal/OSHA by the employer, Decker Electric Co Inc. Electrical Contractors, San Francisco, CA, at 2:26 p.m. on June 11, 2012.