This calculator helps you determine the maximum conduit size required for a given number of conductors. Enter the values below and click “Calculate” to see the max conduit size as per the Canadian Electrical Code (2021 CEC), CSA C22.1:21.
Conduit Fill Calculator
Minimum Recommended Conduit Size:
Conduit Fill:
| Number of conductors: | 1 | 2 | 3 | 4 | More than 4 |
| Conductors (not lead-sheathed) | 53% | 31% | 40% | 40% | 40% |
| Lead sheathed conductors | 55% | 30% | 40% | 38% | 35% |
Calculation Methodology
The CEC employs two methods to calculate the minimum required conduit size using Table 6 or Table 10. Each method works great, however, using Table 10 to obtain the cross sectional area of the wiring method and then using Table 9 to find the interior cross sectional area of the conduit to be installed is the more accurate method. Our calculator utilizes Table 9 and 10 to find the minimum conduit size required for your installation as per Table 8’s conduit fill requirements.
Don’t have the conductor sizes? Click on the link below for a wire size calculator:
