Short answer: For the larger conductor sizes that 314.28 covers, a pull or junction box is sized from the trade sizes of the raceways that enter it and the way the conductors are pulled, not from the volume of the wires under 314.16. A straight pull needs a box length of at least 8 times the trade size of the largest raceway (NEC 314.28(A)(1)). An angle or U pull needs at least 6 times the largest raceway in a row, plus the trade sizes of the other raceways in that same row on the same wall, and each row is figured separately, with the larger result governing (NEC 314.28(A)(2)). Raceway entries that enclose the same conductor must also be separated by at least 6 times the trade size of the larger raceway, measured between the nearest edges of the two entries. Check the conductor size that brings 314.28 into play at the start of the section in your 2026 NEC.
PSI lists Wiring Methods and Materials as a subject area on the Texas Journeyman exam: 10 scored NEC Knowledge questions and 2 scored Calculations questions. PSI does not say how many cover pull box sizing. The Texas Journeyman Practice Pack has 1,000 original questions and 10 timed mock exams in the real two-part format, with step-by-step solutions for every calculation. Try free practice questions without signing up. Get the full pack for US$39 with one payment.
Tsai Electro is an independent learning site. Not affiliated with TDLR, PSI or NFPA. We explain the ideas in our own words and do not reproduce NEC text. Check every rule and table value in your own 2026 NEC, and follow your supervisor and the local inspector.
Box fill or pull box sizing: which one is the question asking?
| The question gives you | Use | What you calculate |
|---|---|---|
| Small conductors, devices, clamps, a box volume in cubic inches | 314.16 box fill | Volume per conductor |
| Large conductors and raceway trade sizes entering from walls | 314.28 | Box dimensions in inches |
If the question lists conductor counts and cubic inches, it is a box fill question, covered step by step in NEC 314 box fill calculation. This page covers only the second row.
The three numbers to remember
- Straight pull: 8 ×. The conductors enter one wall and leave the opposite wall. The box length is at least 8 times the trade size of the largest raceway (NEC 314.28(A)(1)).
- Angle or U pull: 6 × plus the rest of the row. In an angle pull the conductors leave through another wall; in a U pull they leave through the same wall. Boxes with splices are figured the same way. Calculate each row separately. Measure from the entry wall to the opposite wall: 6 times the largest raceway in the row, plus the trade sizes of every other raceway in that row on that wall (NEC 314.28(A)(2)).
- Same conductor, entry to exit: 6 ×. Where one raceway brings a conductor in and another takes the same conductor out, the distance between those two entries is at least 6 times the trade size of the larger raceway (NEC 314.28(A)(2)).
A box that has both a straight pull and an angle pull in the same direction must meet both results, so the larger one governs.
Worked example 1: straight pull
A 3-inch raceway enters the left wall of a box and the same conductors leave a 3-inch raceway on the right wall.
- Find the largest raceway. 3 inches.
- Multiply by 8. 8 × 3 = 24 inches minimum box length, left to right.
Worked example 2: angle pull with one row
On the left wall, one row holds a 3-inch raceway and two 2-inch raceways. All three turn and leave through the top wall.
- Largest raceway in the row × 6. 6 × 3 = 18 inches.
- Add the other raceways in the row. 2 + 2 = 4 inches.
- Left-to-right dimension. 18 + 4 = 22 inches minimum.
- Repeat for the top wall. If the top wall has the same three raceways in one row, the top-to-bottom dimension is also 22 inches.
- Check the same-conductor distance. The 3-inch raceway on the left and the 3-inch raceway on the top enclose the same conductors, so the nearest edges of those two entries must be at least 6 × 3 = 18 inches apart. The 22-inch box dimensions do not prove this by themselves; check where the entries actually sit.
Worked example 3: two rows on one wall
The left wall has two rows. Row 1 holds a 3-inch and a 2-inch raceway. Row 2 holds a 4-inch and a 1-1/2-inch raceway. All turn toward the top wall.
- Row 1. 6 × 3 + 2 = 20 inches.
- Row 2. 6 × 4 + 1.5 = 25.5 inches.
- The larger row governs. The left-to-right dimension is at least 25.5 inches. You do not add the rows together.
Mistakes that cost points
- Using 8 × for an angle pull. 8 × is only for straight pulls.
- Adding every raceway on the wall. For angle pulls, you add only the other raceways in the same row, then compare rows.
- Forgetting the same-conductor distance. A box can meet the wall dimension and still fail the 6 × spacing between the entry and exit of the same conductors.
Power distribution blocks are allowed in pull and junction boxes over 100 cubic inches when they are listed, the box meets the block’s size instructions, the wire bending space meets 312.6, and no uninsulated live parts are exposed with or without the cover; check the rest of 314.28(E) for conductors that pass through without terminating.
Check yourself
- A straight pull uses 2-1/2-inch raceways. Minimum box length? 8 × 2.5 = 20 inches.
- An angle pull row has a 4-inch, a 3-inch and a 2-inch raceway. Minimum dimension? 6 × 4 + 3 + 2 = 29 inches.
- Two rows on one wall give 23 inches and 25.5 inches. Which governs? 25.5 inches.
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Find 314.28 faster on exam day
NFPA 70, National Electrical Code, 2026 Edition (softcover). Write “8 × straight, 6 × angle plus row” in the margin next to 314.28 before exam day, so the rule is one glance away. The Texas exam is open book. PSI allows a soft-bound NEC with highlighting, underlining and notes made in advance. Loose-leaf, spiral-bound and ring-bound copies are not allowed, and only permanent index tabs made or supplied by the NEC publisher are permitted; homemade and third-party tabs are not.
FAQ
How do you size a pull box for a straight pull?
The length is at least 8 times the trade size of the largest raceway entering the box.
How do you size a pull box for an angle pull?
At least 6 times the largest raceway in a row, plus the trade sizes of the other raceways in that row on the same wall. Each row is figured separately and the larger result governs.
What is the spacing between raceways that carry the same conductor?
At least 6 times the trade size of the larger of the two raceways.
Is pull box sizing the same as box fill?
No. Box fill under 314.16 counts conductor volume in cubic inches. Pull box sizing under 314.28 uses raceway trade sizes to set box dimensions.
Is pull box sizing on the Texas Journeyman exam?
Pull box sizing falls within the Wiring Methods and Materials subject area. PSI assigns that area 10 scored NEC Knowledge questions and 2 scored Calculations questions, but does not say how many cover 314.28.
Sources checked October 2026
- PSI Candidate Information Bulletin, Texas electrician examinations (updated September 15, 2026): https://test-takers.psiexams.com/api/content/bulletin/1682
- NFPA 70, National Electrical Code, 2026 Edition, 314.16 and 314.28
