Abstract: A 30-year-old asbestos removal worker was working on a 4000-volt power line in an underground vault. A qualified electrician had previously certified the line to be deenergized. The employee placed his knife on the coating on the deenergized line and received an electric shock, which knocked him back about 1.5 meters. The injured employee exited vault without assistance. He was hospitalized at a burn center for electrical burns on his right little finger and the inside of his left forearm. An investigation by the electric utility and lab tests on the line failed to reveal the cause of the electric shock.