Every person owning or maintaining guy wires in such close proximity to city streets, alleys, and sidewalks as to endanger pedestrians or vehicles shall protect each of such guy wires by attaching thereto at the ground a board not less than six feet in length and three inches in width, or by enclosing such guy wires in a substantial and conspicuous wood or metal guard not less than six feet in length and three inches in diameter or width. Such board or guard shall be painted white or galvanized and shall be securely attached to such guy wires.