Height limits in this chapter shall not apply to transmission or aerial towers, steeples, belfry, cupola, masts, flagpoles or chimneys. However, any freestanding mast, antenna or standard and its supporting structures, guys and anchors shall conform to the applicable setback provisions of this article. Only one (1) flagpole and one (1) radio or television mast or antenna shall be permitted on a lot, except that one (1) per dwelling shall be permitted in the RE and RR-5 zones. The height limits shall not apply to roof-mounted heating, air-conditioning or other mechanical equipment, except that such equipment, when visible from ground level in a residential zone, shall be screened by a wall, cover or by other means and that such screening shall be in keeping with the architectural motif of the building.