Pull Box Size Calculator

Rules and how to enter the layout

Use inch trade-size labels, such as 1-1/4 or 2-1/2. For a straight pull, use the largest raceway in that direction; smaller raceways do not add to the 8× calculation. For angle/U pulls, count the largest entry once at 6× and add every other raceway in the same row, including another entry of the same largest size.

Left/right wall entries constrain length; top/bottom wall entries constrain width. Evaluate each row separately, then take the maximum for that direction. If straight and angle pulls share an axis, satisfy both. A blank axis is “not determined,” never zero inches.

Separately check spacing between entries enclosing the same conductor; the cited angle/U-pull text specifies 6× the larger raceway trade size. The span calculator does not locate openings or verify that spacing. Depth and cover-facing entries also need a separate layout review.

Worked examples

Example 1 — straight pull

Assume 3-inch and 2-inch straight-through raceways along the length. Minimum length = 8 × 3 = 24 in. There is no width input, so the width is not determined by this example.

Example 2 — angle pull, two independent dimensions

Assume one left-wall row of 3, 2 and 1 inches, and one top-wall row of 2 and 1 inches. Length = 6 × 3 + 2 + 1 = 21 in. Width = 6 × 2 + 1 = 13 in. These spans still require an entry-spacing and depth check.

Example 3 — mixed straight and U pulls

Assume a 3-inch straight pull along the length and a length-constraining angle row of 3, 2 and 1 inches. Length = max(8 × 3, 6 × 3 + 2 + 1) = 24 in. For width, a U-pull row of 2, 2 and 1 inches gives 6 × 2 + 2 + 1 = 15 in. A separate row with a 3-inch entry gives 6 × 3 = 18 in, so width = max(15, 18) = 18 in.

Pull-box spans and box-fill volume solve different questions. A dimensional result does not establish the number of conductors permitted in a raceway.