The Ontario Building Code | Wires and Cables
3.1.5.18. wires and Cables
(1) Except as permitted by Sentence (2) and Articles 3.1.5.19. and 3.1.5.21., optical fibre cables and electrical wires and cables with combustible insulationhttp://thehandyforce.com/insulation/" title ="Toronto home insulation">insulation, jackets or sheathes are permitted in a building required to be of noncombustible construction, provided,
(a) the wires and cables exhibit a vertical char of not more than 1.5 m when tested in conformance with the Vertical Flame Test – Cables in Cabletrough in Clause 4.11.4. of CSA C22.2 No. 0.3, "Test Methods for Electrical wires and Cables", (FT4 Rating),
(b) the wires and cables are located in,
(i) totally enclosed noncombustible raceways,
(ii) concealed spaces in walls,
(iii) concrete slabs,
(iv) a service room separated from the remainder of the building by a fire separationhaving a fire-resistance rating not less than 1 h, or
(v) totally enclosed nonmetallic raceways conforming to Clause 3.1.5.20.(1)(b), or
(c) the wires and cables are communication cables used at the service entry to a buildingand are not more than 3 m long.
(2) The requirement in Clause (1)(a) is considered to be met where the wires and cables exhibit a flame-spread of not more than 1.5 m, a smoke density of not more than 0.5 at peak optical density and a smoke density not more than 0.15 at average optical density when tested in conformance with the Flame and Smoke Test in the Appendix to CSA C22.2 No. 0.3, "Test Methods for Electrical Wires and Cables", (FT6 Rating).
In Plain Language
Combustible-jacketed wires and cables are generally allowed in noncombustible-construction buildings if they pass a stricter vertical char test (FT4 rating) or are installed in enclosed noncombustible raceways or similar protected locations, with further detail in the two articles that follow this one.
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.