Exceptions. The maximum height requirements shall not apply to belfries, bulkheads, cupolas or domes not used for human occupancy, nor to chimneys, skylights, church spires, flagpoles, masts, aerials and antennas, monuments, utility poles and ventilators, and ornamental or necessary mechanical appurtenances, provided they are erected only to such height as is necessary to accomplish the purpose they are to serve, provided they are not intended for human occupancy as dwellings, and provided that all such structures and appurtenances to structures shall be erected in conformity with the laws, ordinances and regulations relating to same.