Abstract: An employee working on a transit project was stick welding a steel plate to attach a steering pin to a tunnel shield. He was using a Lincoln IdealArc DC-250 welder (Serial No. 675129). The steel plate measured 460 millimeters by 460 millimeters by 13 millimeters thick (18 inches by 18 inches by 0.5 inches thick). The employee was working by the breast board area of the tunnel shield at the heading of the tunnel. The tunnel was under compressed air and was damp and humid. After he had been welding for about 30 minutes, the welding electrode accidentally contacted his face near the cartoid artery. As a result of the electric shock he received, he lost consciousness momentarily. Coworkers then helped him down to the back of the shield trailing gear at the tunnel floor. The injured employee sustained a minor cut on his head and an erratic heart beat. He was admitted to a hospital for observation. The employee was released from the hospital 48 hours later, but was referred later by the project physician to a psychiatrist for post-accident anxiety syndrome.