The maximum height regulations set forth in Article III, District Regulations, shall not apply to spires, belfries, cupolas, chimneys, ventilators, skylights, flagpoles, utility poles, solar collectors or related equipment, and ornamental or other necessary mechanical appurtenances normally associated with homes, churches and similar establishments. Such appurtenances shall, however, be erected to such height as is necessary to accomplish their intended purpose and shall not be used for human occupancy.