It shall be unlawful for any person, partnership, firm, or corporation, either in person or through his or their employees or agents, to erect or cause to be erected or to maintain any barb wire or electrified fence or any barb wire or electrified string along or upon any fence or string as a barrier within the city limits of the City of Grand Island, except that it shall be permissible to string not more than three strands of barb wire or electrified fence upon supports inclined at an angle not greater than sixty degrees with the horizontal plane, when such wires are strung so that they are suspended above and within the privately owned enclosed property, and the bottom strand of such barb wire or electrified fence is not less than six feet above the surface of the ground.