When a junction box is required
With conduit and cable wiring, every outlet, switch, splice, junction, termination, wiring method transition and pull point needs a box or conduit body, unless a specific exception in the code allows something else.
What the code requires
For conduit, tubing, and cable wiring methods such as AC, MC, MI and NM cable, the code requires a box or conduit body at each outlet point, switch point, splice point, junction point, termination point, wiring method transition point and pull point, unless one of the specific allowances in 300.15(A) through (L) applies.
Fittings and connectors may be used only with the wiring methods they are designed and listed for. Concealed knob-and-tube wiring needs a box at every outlet and switch point.
On the job
- Splices buried in a wall or ceiling with no box are a common correction.
- Unless one of the specific allowances applies, a splice point needs a box or conduit body, so a splice cannot simply be taped and hidden in the framing.
Exceptions that matter
- An identified fitting may be used instead of a box where the conductors are not spliced or terminated in it. It must stay accessible unless it is listed for concealment.
- Direct-buried conductors and cables do not need a box at splices and taps made under 300.5(E).
What changed in 2023
The 2023 edition added wiring method transition points, such as where one cable or raceway type changes to another, to the list of places that need a box or conduit body.
Related sections
- NEC 300.5(E)
- NEC 314.29: Junction boxes must stay accessible
- NEC 334.40
Where this comes from
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Kyle Robert Anderson KBC Electric · CSLB #1073066 · C-10 Electrical · Licensed since 2021