WireWicket / NEC 314 · 2026 reference data

Box fill & pull-box sizing

Add each applicable fill allowance or check minimum pull-box dimensions. The calculation uses fixed NEC 2026 reference data; a project’s selected edition remains separate.

Calculation inputs
Enter the installed conductors and fittings, or the pull-box raceway rows and enclosure dimensions.
NEC 314 calculation mode
Box and available volume

Custom volume scales the listed volume by measured interior depth relative to the listed depth. This is an estimate, not a Table-listed volume; verify the enclosure and any extension or ring volume with its product listing.

Conductors and qualifying loops

Count conductors under 314.16(B)(1), including those entering, terminating, spliced, or passing through. Enter equipment grounding conductors separately below. Mark qualifying unbroken loops at least twice the 6 in minimum free-conductor length; each is counted one extra time.

18 AWG
16 AWG
14 AWG
12 AWG
10 AWG
8 AWG
6 AWG
Fittings and devices
Calculation result
Deterministic reference arithmetic · NFPA 70 (NEC) 2026

Within selected box volume

0.75 in³ remaining.

Required volume
20.25 in³
Selected box volume
21.00 in³
Remaining volume
0.75 in³

Allowance breakdown

  • Conductors and qualifying long loops 314.16(B)(1)

    6 × 12 AWG at 2.25 in³

    13.50 in³

  • Device yokes / straps 314.16(B)(4)

    1 yoke(s) × 2 × 12 AWG allowance (2.25 in³)

    4.50 in³

  • Equipment grounding / bonding conductors 314.16(B)(5)

    1 conductor(s): 1 allowance for the first four + ¼ allowance for each additional conductor, based on 12 AWG (2.25 in³)

    2.25 in³

21.00 in³ listed volume (Table 314.16(A))

NEC references · NFPA 70 (NEC) 2026View NFPA 70 (2026) in NFPA LiNK

Box fill: 314.16(A), Table 314.16(A), 314.16(B)(1)–(6), and Table 314.16(B)(4). Pull boxes: 314.28(A)(1)–(2). A project’s selected NEC edition is shown as project context and does not change this fixed 2026 data set.

Reference aid only. Verify the edition adopted by the jurisdiction, local amendments, box listing and project conditions with the authority having jurisdiction. This calculation does not replace professional design or inspection.