A pull box is used for a straight pull, and the largest raceway entering it is 3 inch trade size. What is the minimum required length of the box in the direction of the pull?

Explanation

For straight pulls, the box length must be at least eight times the trade size of the largest raceway: 8 x 3 = 24 inches. The 18-inch answer uses a factor of six, which applies to angle and U pulls, and 12 inches uses a factor of four that appears nowhere in the rule.