Mechanical equipment, open or enclosed, may be located on the roof of a building in accordance with the following provisions:
(a) Mechanical equipment shall not exceed the maximum height of mechanical equipment specified for each Parcel as set forth in Appendix B of this Chapter and shall be measured from the roof level of the highest story of the building. Such mechanical equipment may penetrate the maximum building height specified for each Parcel as set forth in Appendix B.
(b) Such mechanical equipment shall be set back at least 10 feet from the upper street wall of the building. In addition, such equipment shall not penetrate a sky exposure plane that begins at the point of intersection of the roof and the upper street wall of the building, and rises over the building at a slope of 2.7 feet of vertical distance for each foot of horizontal distance, except for permitted obstructions set forth in Section 104-322. Where portions of the upper street wall are located at different distances from the street line or mandatory widened sidewalk line, whichever is applicable, the portion used to establish such reference line shall be the portion that occupies the greatest area of such upper street wall.
(c) Such mechanical equipment shall not overhang any recess in the building wall that is open to the sky.