CEC box fill calculator
Plan junction box and device box sizes with a Canadian box fill calculator aligned with CE Code volume rules—ideal when you are documenting conductor counts, devices, and splices for inspection-ready packages.
Related: conduit fill calculator, tap conductor calculator.
How this calculator works
Enter box type, internal volume, conductor sizes and counts, devices, and fittings. The app compares total required volume to the box allowance.
CE Code alignment
Logic follows Canadian Electrical Code practice for box fill. Confirm any local amendments and manufacturer data for specialty boxes.
Run in the app
Sign in to run the box fill calculator.
FAQ
- What is a box fill calculator used for?
- It totals conductor volumes, devices, clamps, and fittings inside a box or fitting so you can verify the enclosure is large enough under Canadian box fill rules.
- Does this cover junction boxes and device boxes?
- Yes. You can model typical junction and device box layouts with the counts and types you expect in the finished installation.
- Do I still need to verify box fill in the field?
- Always confirm actual conductor sizes, splices, and devices installed. The calculator supports planning and documentation; field conditions remain authoritative.