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Wire sizing in Canada follows the Canadian Electrical Code (CEC), Part I, Section 4 and Table 2 rather than the NEC's Table 310.16. Both codes use similar concepts — allowable ampacity at a reference temperature with derating for ambient temperature and bundling — but the specific values, table formats, and terminology differ in ways that matter for Canadian permit submittals.
CEC Table 2 provides allowable ampacities for conductors in free air and in conduit (raceway) at a 30°C ambient temperature. The table is organized by conductor material (copper and aluminum), insulation type (XLPE, RW90, TWU75, etc.), and number of current-carrying conductors in a raceway. Unlike NEC Table 310.16, which uses a single combined table for conductors in raceway and correction factors applied separately, CEC Table 2 directly provides the derated ampacity for common bundling scenarios. This makes the CEC table somewhat more straightforward for common residential and commercial applications.
Key differences from NEC that Canadian electricians encounter:
The CEC uses RW90 (90°C XLPE) as the dominant insulation type for general wiring, comparable to NEC THHN/THWN-2. However, the terminal temperature rating rule in the CEC still limits ampacity to the 75°C column at most standard terminals, paralleling the NEC 110.14(C) requirement.
CEC Section 4-004 sets the general rule that conductor ampacity must not be less than the load connected to it, with continuous load adjustments handled through the Section 8 load calculation rules rather than a separate 125% multiplier at the conductor level (though the OCPD sizing still reflects continuous load requirements).
SparkShift's wire size calculator applies CEC Table 2 values when the CEC mode is selected, including ambient temperature correction factors from Table D3 and bundling derating for multiple conductors in a raceway. The results panel cites the applicable CEC section for permit documentation.
SparkShift pre-selects CEC mode. Results cite CEC rules (Section 4) for permit documentation.
Open CEC wire size calculator →Each Canadian province and territory has adopted a version of the CEC. Verify the adopted edition and local amendments with your AHJ.
CEC Table 2 (in CSA C22.1) provides allowable ampacities for copper and aluminum conductors by insulation type and installation method. It is the Canadian equivalent of NEC Table 310.16.
RW90 is a 90°C-rated cross-linked polyethylene (XLPE) insulated conductor used in Canadian wiring, equivalent in thermal rating to NEC THHN/THWN-2. The CEC uses RW90 for most conduit installations; the NEC uses THHN/THWN-2. Ampacity values are similar but not identical.
The CEC handles continuous load sizing through Section 8 load calculation methods and OCPD sizing rules rather than a standalone 125% conductor derating. The net result is similar — conductors and OCPDs must be sized for continuous loads — but the mechanism differs from NEC 210.20(A).
All provincial and territorial electrical codes derived from CSA C22.1 use CEC Table 2. Ontario's OESC, BC Electrical Safety Regulation, Alberta's Safety Codes Act electrical regulations, and all other provincial codes reference CEC Table 2 for conductor ampacity.
Disclaimer: SparkShift calculators are provided for informational purposes. Always verify calculations against the adopted CEC edition in your province and confirm requirements with your local authority having jurisdiction (AHJ) before commencing work. The CEC edition adopted may differ by province — Ontario uses the OESC, BC uses the BC Electrical Safety Regulation, and other provinces have their own adopted editions.