Abstract: A water main connection crew for a city water department was making a connection from a contractor's pipe to a city water line. Employee #4 had opened the trench with his backhoe and was seated on the backhoe. Employee #1 was in the trench, using a jackhammer. Employee #2 was also in the trench, about 7 feet away with his back turned, working on another pipe connection. Employee #3 was sitting out of the trench, working on tools. The trench was about 5 to 6 feet deep without shoring or sloping. Employee #1 started using the jackhammer to complete removing what he thought was a kick block. However, this was the concrete cover over a conduit housing a 69-kilovolt underground cable. The chisel on the jackhammer punctured the conduit wall three times, then the fourth time it contacted the power line. This caused an electrical fault. As a result of the ensuing electric arc, employee #1 saw a bright flash and was pushed away from the jackhammer. Employee #2, who was slightly injured by the electric arc, exited the trench on his own. A city crew working across the street ran over and pulled employee #1, who had sustained an electric shock and burns to his lower limbs, from the trench. (Current entry and exit points were employee #1's left thigh, where the jackhammer was touching him, and the ball of his right foot.) Emergency medical services transported employees #1 and #2 to a hospital. Employee #2 was treated and released. Employee #1 was hospitalized for an anticipated 1 to 2 weeks for his injuries. Employees #3 and #4 were not injured, even though they were listed on injury lines in the original abstract. There was no evidence that the Miss Utility service had been called to mark utility lines in the area.