CEC Table 2
Ampacity of Insulated Conductors
Just like NEC Table 310.16, CEC Table 2 answers the fundamental question: how much current can this wire safely carry? The table covers copper conductors rated up to 5,000 volts with no more than three current-carrying conductors in a raceway or cable, at a 30-degree-C ambient temperature. The ampacity values are organized by conductor size and insulation temperature rating. However, there are some important differences between the Canadian and American approaches. CEC Rule 4-006 governs how you apply terminal temperature limitations, and it handles the interaction between conductor temperature ratings and terminal ratings somewhat differently than NEC 110.14(C). Derating for temperature is handled through CEC Table 5A (similar to NEC 310.15(B)), and derating for multiple conductors is in CEC Table 5C (similar to NEC 310.15(C)). Canadian electricians need to be familiar with both Table 2 for copper and Table 4 for aluminum conductors.
When You Need This
- Sizing conductors for any electrical installation governed by the Canadian Electrical Code
- Cross-referencing ampacity values between NEC and CEC for a cross-border project
- Performing a conductor sizing calculation for a Canadian residential or commercial project
- Preparing for the Red Seal exam or a Canadian provincial electrical licensing exam
Key Points
Common Mistakes
Assuming CEC Table 2 values are identical to NEC Table 310.16 — there are differences in some wire sizes
Using NEC derating tables instead of CEC Tables 5A and 5C when working under the Canadian code
Ignoring CEC Rule 4-006 terminal temperature limits and using the raw 90-degree-C column as the final ampacity
Looking up aluminum conductors in Table 2 — aluminum is in Table 4, not Table 2
Applying NEC 110.14(C) rules instead of CEC Rule 4-006 — the approaches differ in some details
Exam Tip
For the Red Seal exam, know that Table 2 is for copper and Table 4 is for aluminum. The derating process is similar to the NEC: start with the table ampacity, apply temperature correction from Table 5A, apply conductor count adjustment from Table 5C, and then check terminal temperature limits per Rule 4-006.
Frequently Asked Questions
The CEC and NEC are developed by different standards organizations (CSA Group and NFPA respectively) using different testing methodologies and safety margins. While the underlying physics is the same, the resulting tables can differ slightly due to differences in assumptions about installation conditions, conductor construction, and safety factors.
No. If the installation is governed by the Canadian Electrical Code, you must use CEC tables. Using the wrong code table could result in improperly sized conductors and would not pass inspection under the CEC.
CEC Table 1 covers free-air ampacities for copper conductors, and CEC Table 3 covers free-air ampacities for aluminum. These are the CEC equivalents of NEC Table 310.17.
Inline Tools
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Related Code Sections
This is an educational summary, not the official code text. The NEC® is a registered trademark and copyright © National Fire Protection Association (NFPA). The CEC is copyright © CSA Group. For official code text, visit nfpa.org or csagroup.org. SparkShift is not affiliated with NFPA or CSA Group.