Canadian Electrical Code — CEC Table 2, Wire Sizing & Standards Reference

What is the Canadian Electrical Code (CEC)?

The Canadian Electrical Code, Part I (CSA C22.1) is the national standard that governs electrical installations in Canada. It is published by CSA Group and adopted — with provincial amendments — by all 10 provinces and 3 territories. The current edition in wide adoption is the 2021 edition (C22.1-21); the 2024 edition has been published and provinces are in various stages of adoption.

The CEC is not the same as the American National Electrical Code (NEC). Canadian electricians work to CEC rules; American tools, tables, and wire sizing charts do not apply. The conductor ampacity values in CEC Table 2 differ from NEC Table 310.16, and the demand methods in CEC Rules 8-200 through 8-210 differ substantially from NEC load calculation methods.

Use our wire size calculator, circuit breaker sizing calculator, electrical load calculator, and voltage drop calculator — all built to CEC, not NEC.

CEC Table 2 — Copper Conductor Ampacity Chart

CEC Table 2 lists the allowable ampacity (current-carrying capacity) for copper conductors based on wire size, insulation temperature rating, and installation method. The values below are for conductors in conduit or raceway — the most common residential and commercial installation. Values in free air are higher.

RW75 is the most common residential conductor insulation (75°C rated, RW designation). T90 (90°C rated) is common in commercial work and allows higher ampacity in the same wire size.

Note: CEC Section 12-2202 limits 14 AWG branch circuit conductors to 15A breakers and 12 AWG to 20A breakers regardless of the Table 2 ampacity values. Temperature correction factors apply when more than 3 current-carrying conductors share a raceway (CEC Table 5C). Always verify final sizing with the licensed electrician performing the work.

Wire Size Quick Selection Guide

The table below maps circuit breaker size to the minimum wire size required by CEC Table 2 for copper and aluminum conductors. Aluminum conductors are common in service entrances and large feeder applications but are not used for small branch circuits in Canada.

For long runs where voltage drop exceeds 3% (CEC Rule 8-102), the conductor must be upsized regardless of the breaker size. Use the voltage drop calculator to check whether your run length requires upsizing.

Provincial Amendments to the Canadian Electrical Code

Each province adopts the base CEC with its own amendments. The amendments are typically minor modifications and additions to the national standard — the base CEC applies everywhere, but electricians must also know the amendments for their province.

Voltage drop — when to upsize the wire

CEC Rule 8-102 recommends limiting voltage drop to 3% on branch circuits and 5% total (combined feeder and branch circuit). For runs longer than 30 metres, voltage drop often requires upsizing beyond the minimum Table 2 ampacity. The formula:

VD (%) = (ρ × 2 × L × I) / (A × V) × 100

Where:
  ρ = resistivity (0.0172 Ω·mm²/m for copper, 0.0282 for aluminum)
  L = one-way run length in metres
  I = current in amperes
  A = conductor cross-section in mm²
  V = supply voltage (120V or 240V)

Use the voltage drop calculator to check any circuit automatically.