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EPISODE 11 — Boxes, Conduit Bodies & Fittings: Where They're Required (and Where They're Not) (300.17)
EPISODE 11 — Boxes, Conduit Bodies & Fittings: Where They're Required (and Where They're Not) (300.17)
Slide 1 — Hook "One long, list-heavy section today — when you actually need a box, and the 12 situations where you don't."
Slide 2 — The general rule
A box is required at each outlet/switch point for concealed knob-and-tube wiring.
Fittings/connectors can only be used with the specific wiring methods they're designed and listed for.
For conduit/tubing/AC/MC/MI/NM/other cable: a box or conduit body is required at every outlet, switch, splice, junction, termination, wiring-method-transition, or pull point — UNLESS one of the 12 exceptions in 300.17(A)-(L) applies.
Slide 3 — The 12 "you don't need a box here" situations (A) Wiring methods with accessible removable covers (wireways, multioutlet assemblies, auxiliary gutters, surface raceways). (B) Equipment with an integral junction box/wiring compartment. (C) Cable entering/exiting conduit used purely for support/protection (with an end fitting to prevent abrasion). (D) Accessible straight-through splice fittings in Type MI cable. (E) Wiring devices with an identified integral enclosure and wall/ceiling-fastening brackets for NM cable. (F) An identified fitting where conductors aren't spliced/terminated inside it (must stay accessible if used as a pull point). (G) Direct-buried splices/taps per 300.7(E). (H) Insulated devices supplied by NM cable per 334.40(B). (I) Splices/switches/terminals/pull points already inside a cabinet, cutout box, or listed switch/OCPD/motor controller/MCC enclosure. (J) Luminaires used as a raceway per 410.64. (K) Embedded splices permitted under specific heating-equipment sections. (L) Conductors in manholes/handhole enclosures, except where connecting to equipment.
Slide 4 — Quiz + CTA Q: "Is a box required for a splice made inside a listed cabinet or cutout box?" A) Yes, always B) No — 300.17(I) exempts splices already inside those enclosures C) Only for splices over 6 AWG D) Only in commercial buildings
✅ Answer: B — 300.17(I): a splice/switch/terminal/pull point already in a cabinet, cutout box, or similar listed enclosure doesn't need a separate box.
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⚠️ Educational NoticeQuick Hits are educational explanations based on my understanding of the NEC. Always verify requirements in the current adopted NEC, applicable local amendments, manufacturer instructions, and with the AHJ.
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