National Building Code Standards for Wires and Cables in Noncombustible Construction
Adhering to the National Building Code of Canada is critical for ensuring the safety and compliance of any modern structure. At empcontracting.ca Inc. your construction contractor in London, Ontario, we prioritize these technical standards to ensure every project meets the highest fire safety requirements for noncombustible construction.
Understanding NBC 3.1.5.21: Wires and Cables in Noncombustible Construction
In buildings where noncombustible construction is mandated, the use of optical fibre and electrical cables with combustible insulation or jackets is permitted only under specific conditions. These regulations prevent the rapid spread of fire through electrical systems.
The FT4 Rating and Vertical Flame Tests
According to Article 3.1.5.21, cables must exhibit a vertical char of no more than 1.5 m when subjected to the Vertical Flame Test (FT4 rating) in conformance with CSA C22.2 No. 0.3. Furthermore, these cables must be strategically located within:
- Totally enclosed noncombustible raceways
- Masonry walls or concrete slabs
- Service rooms separated by a fire-resistance rating of at least 1 hour
- Totally enclosed non-metallic raceways meeting Clause 3.1.5.23.(1)(b)
Regulations for Voice, Sound, and Data Cables in Plenums
Special considerations are required for communication cables located in plenums. Unless housed in noncombustible raceways, these cables must meet the FT6 rating (CAN/ULC-S102.4). This ensures:
- A horizontal flame distance of not more than 1.5 m
- An average optical smoke density not exceeding 0.15
- A peak optical smoke density not exceeding 0.5
Exemptions for Fire Alarm Systems
It is important to note that cables and wires within plenums used for fire alarm signal transmission are not required to meet the specific horizontal flame and smoke density requirements of Sentences (2) and (3), providing a necessary allowance for critical safety infrastructure.
Elevator Cables and Non-metallic Raceways
Combustible Travelling Cables (3.1.5.22)
The building code permits the use of combustible travelling cables for elevating devices, recognizing the mechanical requirements of elevator operation within noncombustible building shells.
Non-metallic Raceway Limitations (3.1.5.23)
Non-metallic raceways are permitted within fire compartments, provided they do not exceed an outside diameter of 175 mm. These components must also comply with Article 3.1.9.2 regarding the penetration of fire separations to maintain the integrity of the building's fire safety plan.
Navigating these complex codes requires professional expertise. For reliable and code-compliant building solutions, contact empcontracting.ca Inc. your construction contractor in London, Ontario today.