Electrical reference chart
Pull Box Sizing Chart
Use this pull box sizing chart after the calculator result to document straight pulls, angle pulls, U-pulls, splices, raceway entries, bend radius, and cover access before selecting a listed enclosure.
Quick reference table
Pull box sizing starts with the pull geometry, not total wire count. Use the calculator worksheet to classify straight, angle, U-pull, splice, or cable-pull conditions, then verify enclosure dimensions, conductor bending space, cable radius, equipment instructions, adopted NEC requirements, and AHJ review.
Pull box sizing route classification
| Field condition | Record before calculating | Why it changes the box |
|---|---|---|
| Straight pull | Raceway trade size and opposite entry walls | Controls the straight pulling dimension |
| Angle pull | Raceways entering adjacent walls and spacing between entries | Requires wall and entry spacing checks |
| U-pull | Raceways entering and leaving the same wall | Spacing and wall dimension can control enclosure size |
| Spliced conductors | Conductor size, splice count, and bend space | Adds room for splices and conductor routing |
| Cable assembly pull | Cable outside diameter, minimum bend radius, and pull direction | Physical cable handling can exceed raceway-based dimensions |
After the pull box calculator result
| Result looks acceptable | Field check | Why it still matters |
|---|---|---|
| Minimum dimension found | Can the cover be opened and conductors worked safely? | Access can make a larger enclosure practical |
| Large raceways enter one side | Are locknuts, bushings, and fittings crowding each other? | Fitting layout can break a clean paper calculation |
| Splices included | Is conductor bending space and splice kit space documented? | Splice hardware occupies usable volume |
| Long pull planned | Does pulling tension require another pull point? | Mechanical stress can drive extra boxes |
How to use this chart
Classify the pull first
Identify straight pull, angle pull, U-pull, splice condition, or cable assembly pull before entering dimensions in the calculator.
Sketch every raceway entry
Record trade size, wall location, spacing, fitting layout, and pull direction so the calculator result reflects the actual route.
Review access and bend space
After the result, compare the selected enclosure with conductor bend radius, splice kit space, cover access, pulling equipment, and field installation room.
Formula basis
Pull box screen = identify pull type and controlling raceway size, then apply the calculator method for straight, angle, U-pull, splice, or cable bending conditions.
- Pull type determines whether the worksheet follows straight, angle, U-pull, splice, or cable-bend logic.
- Largest raceway size and entry wall locations often control the minimum enclosure dimensions.
- Splices, cable outside diameter, and bend radius can require more space than a minimum raceway screen.
Worked examples
Angle pull with large conduits
Document the largest raceway, each entry wall, entry spacing, and pull direction before the calculator result is compared with a listed enclosure.
Splice box in a feeder run
A box that passes the pull dimension screen can still be too small for splice kits, conductor bending space, and future service access, so the worksheet should include splice hardware notes.
Related calculators
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.
Conduit Fill Calculator
Calculate conduit fill percentages, maximum wire counts, and conduit sizing per NEC requirements
Cable Pulling Tension Calculator
Calculate maximum pulling tension and sidewall pressure for cable installations. Verify pulls are within conductor limits per NEC 300.34 and manufacturer specifications.
Related charts
Conduit Fill Chart
Plan conduit fill from finished conductor area, raceway type, trade size, conductor count, bends, pulling conditions, and derating follow-up.
Cable Pulling Tension Chart
Plan cable pulling tension from route sections, bends, cable weight, friction assumptions, lubricant, sidewall pressure, and manufacturer limits.
Box Fill Chart
Plan box fill from conductors, devices, internal clamps, equipment grounds, fittings, pigtails, and marked box volume.
Frequently asked questions
These answers explain how to use the chart without turning a quick reference into a final design decision.