The Ontario Building Code | Light Diffusers and Lenses
3.1.13.4. light Diffusers and Lenses
(1) The flame-spread rating of combustible light diffusers and lenses in all occupancies other than Group A, Division 1 is permitted to be more than the flame-spread rating limits required elsewhere in this Subsection, provided the light diffusers and lenses,
(a) have a flame-spread rating not more than 250 and a smoke developed classification not more than 600 when tested in conformance with CAN/ulc-S102.2, "Test for surface Burning Characteristics of flooring="http://thehandyforce.com/flooring/" title ="Handyman flooring install Toronto">flooring, Floor Coverings, and Miscellaneous Materials and Assemblies",
(b) fall to the bottom of the test apparatus before igniting when tested in conformance with ulc-S102.3, "Fire Test of light Diffusers and Lenses",
(c) are not prevented from falling from the ceiling by construction located beneath the elements, and
(d) are not used in a corridor that is required to be separated from the remainder of the buildingby a fire separation or in an exitshaft unless individual diffusers or lenses are not more than 1 m2in area and are not less than 1.2 m apart.
In Plain Language
Combustible light diffusers and lenses (outside Group A, Division 1 occupancies) can exceed the usual flame-spread limits provided they meet specific alternate criteria: a 250 flame-spread rating, 600 smoke-developed classification under CAN/ULC-S102.2 testing, and behavior (like falling away) described further in the article.
This is a plain-language summary of the 2012/2017 Ontario Building Code text above, for general understanding only and not a substitute for the Code. Always confirm current requirements against the 2024 edition (O.Reg. 163/24) or a qualified professional before construction.