*Sizing Pull Boxes — Art. 370*

Choose the best answer. (Assume all conductors pulled through the conduits in Questions 1-5 are No. 4 and larger.)

**1.** What is the minimum length pull box required for a straight pull having a run of 2-in. conduit entering and leaving opposite walls of the box?

(a) 12 in.

(c) 16 in.

(b) 14 in.

(d) 18 in.

**2.** What is the minimum size pull box required for a straight pull having parallel runs of 2½-in., 2-in., and 1½-in. conduit entering and leaving opposite walls of the box?

(a) 14 in.

(c) 18 in.

(b) 16 in.

(d) 20 in.

**3.** What is the minimum size pull box required for an angle pull with a run of 2-in. conduit that enters the top left wall and leaves the bottom right wall of the box?

(a) 8 in. x 8 in.

(b) 12 in. x 12 in.

(c) 14 in. x 14 in.

(d) 16 in. x 16 in.

**4.** What is the minimum size pull box required for an angle pull with runs of 4-in., 3-in., and 2-in. conduit entering and leaving the box?

(a) 29 in. x 29 in.

(b) 30 in. x 30 in.

(c) 32 in. x 32 in.

(d) 36 in. x 36 in.

**5.** What is the minimum size pull box required for a U-pull having a run of 2-in. conduit?

(a) 10 in. x 10 in.

(b) 12 in. x 12 in.

(c) 14 in. x 14 in.

(d) 16 in. x 16 in.

**Answers and Discussion**

**1. (c).** When sizing a pull box for a straight pull (conduits on opposite walls), multiply the dimension of the largest size conduit entering and leaving the box by a specified multiplier.

*Step 1:* Find the appropriate multiplier in Sec. 370-28(a)(1).

Multiplier = 8

*Step 2:* Calculate the required length.

2 in. x 8 = 16 in.

*Solution:* The minimum length of the pull box is 16 in.

*Stallcup’s Code Loop: Sec. 370-28(a) and 370-28(a)(1).*

**2. (d).** Junction boxes with more than two conduits connected to their sides (to form a straight pull) are sized by multiplying the trade diameter of the largest raceway by a specified multiplier. The dimensions of the remaining conduits do not factor into this calculation.

*Step 1:* Find the appropriate multiplier in Sec. 370-28(a)(1).

Multiplier = 8

*Step 2:* Calculate the required length.

2½ in. x 8 = 20 in.

*Solution:* The minimum length of the pull box is 20 in.

*Stallcup’s Code Loop:* Sec. 370-28(a) and 370-28(a)(1).

**3. (b).** When sizing a pull box for an angle pull, multiply the trade diameter of the largest conduit entering and leaving by a specified multiplier.

*Step 1:* Find the appropriate multiplier in Sec. 370-28(a)(2).

Multiplier = 6

*Step 2:* Calculate the required length.

2 in. x 6 = 12 in.

*Solution:* The minimum dimension of the pull box is 12 in. x 12 in.

*Stallcup’s Code Loop:* Sec. 370-28 and 370-28(a)(2).

**4. (a).** Junction boxes with more than one run of conduit connected to their walls to form an angle pull are sized by multiplying the trade diameter of the largest conduit by a specified multiplier and adding the dimensions of the remaining conduits to this value.

*Step 1:* Find the appropriate multiplier in Sec. 370-28(a)(2).

Multiplier = 6

*Step 2:* Calculate the required length.

4 in. x 6 = 24 in.

*Step 3:* Now add the diameters of the remaining conduits.

24 in. + 3 in. + 2 in. = 29 in.

*Solution:* The minimum dimension of the pull box is 29 in. x 29 in.

*Stallcup’s Code Loop:* Sec. 370-28 and 370-28(a)(2)

**5. (b).** Junction boxes with more than one run of conduit connected to their walls to form a U-pull are sized by multiplying the trade diameter of the largest conduit by a specified multiplier and adding the dimensions of the remaining conduits to this value.

*Step 1:* Find the appropriate multiplier in Sec. 370-28(a)(2).

Multiplier = 6

*Step 2:* Calculate the required length.

2 in. x 6 = 12 in.

*Solution:* The minimum dimension of the pull box is 12 in. x 12 in.

*Stallcup’s Code Loop:* Sec. 370-28(a) and 370-28(a)(2).