EdgeSpace Box Fill

EdgeSpace Box Fill is an offline NEC 314.16 device-box volume checker for electricians and inspectors. Pick a listed metal box (or a marked custom volume), the largest conductor AWG, and counts for conductors, device yokes, internal clamps, support fittings, and equipment grounding conductors. See required volume, box volume, fill used, PASS/FAIL, and a line-by-line 314.16(B) breakdown. This is box fill — not conduit fill and not voltage drop. WHAT YOU GET • NEC 2023 Table 314.16(A) metal-box volumes • Table 314.16(B)(1) allowances for 18–6 AWG • Conductors, clamps, support fittings, devices, equipment grounding • 2023 314.16(B)(5) extra-EGC quarter allowances • in³ and cm³ (NEC note: 1 in³ = 16.4 cm³) • Box diagram, share, copy, and PDF • History and favorites • Fully offline — no account, no ads, no subscription One-time purchase. Always verify the adopted code edition and marked box volume. Copyright © 2026 EdgeSpace.