(1) Except as permitted in Sentences (2) and (3), openings through guards shall be of a size that prevents the passage of a spherical object having a diameter of 100 mm.
(2) Except where they serve storage garages, guards in industrial occupancies are permitted to consist of,
(a) a top railing, and
(b) one or more horizontal intermediate rails spaced such that the size of the openings through the guard prevents the passage of a spherical object having a diameter of 535 mm.
(3) Openings through any guard that is not required by Article 9.8.8.1. and that serves an occupancy other than industrial occupancy, shall be of a size that,
(a) prevents the passage of a spherical object having a diameter of 100 mm, or
(b) permits the passage of a spherical object having a diameter of 200 mm.