Conduit Fill Calculator Canada (CEC Raceway Fill Calculator)
Based on CEC 2024 Table 9G (conduit) and Table 6A (insulated conductor area), with Rule 12-910 fill limits. Select wire insulation, AWG/kcmil size, and conduit type.
Conductors
Pick insulation type (Table 6A) and conductor size for each row.
Conduit / Tubing
Choose raceway type (Table 9G) and trade size.
Ampacity Derating — CEC Table 5C
Rule 4-004(2): correction for more than 3 current-carrying conductors in a raceway or cable.
Applied factor
100%
Based on 3 conductors entered above. Count only current-carrying conductors when applying in the field.
| # of current-carrying conductors | Ampacity correction |
|---|---|
| 1 – 3 | 100% |
| 4 – 6 | 80% |
| 7 – 24 | 70% |
| 25 – 42 | 60% |
| 43 and above | 50% |
Apply this factor to the Table 2 (or applicable) ampacity before continuous-load adjustments. Neutrals of balanced 3-wire and 4-wire wye circuits are not normally counted; harmonic-rich loads may require counting per Rule 4-004(3). Always confirm against the current CEC.
Derated Ampacity — CEC Table 2 (Copper, in raceway)
Base ampacity × Table 5C correction factor (30 °C ambient).
| Conductor | Temp col. | Base ampacity | × 100% | Derated ampacity |
|---|---|---|---|---|
| 12 AWG — TWN75 / T90 Nylon | 90 °C | 40 A | × 1.00 | 40 A |
Values from CEC Table 2 (copper, not more than 3 conductors in a raceway, 30 °C ambient). The derated value above already accounts for Table 5C. Apply additional Table 5A correction if ambient differs from 30 °C, and respect Rule 4-006: equipment termination temperature (typically 75 °C) caps the usable ampacity regardless of the conductor's insulation rating.