Category
NEC Code Compliance calculators
NEC 314 box-fill and pull-box sizing checks for U.S. rough-in and installation planning
2
Calculators in category
6
Related categories
Pull Box Sizing Calculator
Screen straight, angle, and U-pull box dimensions from NEC 314.28 using governing raceway rows and the trade size of the largest raceway.
Box Fill Calculator
Calculate electrical box fill requirements per NEC 314.16. Determine if your outlet box, junction box, or switch box has sufficient volume for conductors, devices, and fittings.
NEC Code Compliance Overview
The NEC compliance category focuses on NEC 314 box-fill and pull-box screening for U.S. rough-in work. The tools support early layout review when conductor count, fittings, bends, and raceway geometry determine whether the installation can proceed without rework.
Application guidance
Review the operating assumptions, installation conditions, and code checkpoints that most often affect results in this category.
Rough-in timing and layout risk
Box fill and pull-box questions are easiest to correct before conductors are pulled and covers go on. The category is built for layout screening early enough to prevent expensive rework.
- Device and junction boxes are best reviewed before conductor count and equipment allowances are effectively locked in.
- Pull-box dimensions are easier to revise before long runs or large raceways are installed.
- The result is most useful while the layout can still absorb a plan-review change without rework.
Volume allowances and pull geometry
This category is narrow on purpose. One calculator is about cubic-inch volume allowances inside a box; the other is about physical dimensions and conductor pull geometry.
- Box-fill review applies when conductor allowances, device allowances, and internal clamp adjustments are the governing issue.
- Pull-box sizing applies when straight pull, angle pull, or U-pull clearance drives the decision.
- The two tools answer different NEC 314 questions and should not be treated as interchangeable.
Field layout and listing verification
The calculator result still depends on the actual fittings, raceway arrangement, and equipment listing that will be installed. That final confirmation belongs in the plan set and field review.
- Raceway sizes, conductor count, and entry arrangement still need to match the actual layout.
- Manufacturer limitations remain relevant when listed enclosures or pull sections add their own requirements.
- The adopted NEC edition and any local amendment should align with the governing project documents.