NORWALK - A privately owned plow clearing snow during the storm rolled into an electrical vault in Norwalk this morning. The plow driver says he was clearing the sidewalk in front of City Supermarket on West Avenue when the plow accidentally lifted the cover off an underground electrical pit.Then the back tire rolled into the pit. Firefighters called Connecticut Light and Power (CL&P) to come help with the situation."We always err on the side of caution when anything electrical is involved," says Deputy Chief Chris King, of the Norwalk Fire Department. "CL&P are the experts when it comes to that."The driver of the plow was not hurt.