NEC 2023 · Sections 404.2(C) & 404.9(B)
NEC 404.2(C) — Neutral at Switch Locations
The end of the old two-wire switch loop. Smart switches, dimmers, and occupancy sensors need a neutral to power their electronics — so the code makes you land one at the switch box up front instead of stealing the ground for it later.
Where the Neutral Is Required
- • Switches controlling lighting loads supplied by a grounded general-purpose branch circuit.
- • In habitable rooms and bathrooms of dwellings, and other locations per the section's scope.
- • The neutral doesn't have to be spliced to anything — it just has to be present in the box (capped is fine) so a future device can use it.
- • Where multiple switch locations control the same lighting, at least one location must have the neutral.
The Exceptions That Matter in the Field
- • Raceway jobs: if the conductors arrive in a raceway big enough to pull a neutral in later, you don't need to land one now.
- • Accessible framing: cable entering through a framing cavity open at the top or bottom on the same floor — or through a wall unfinished on one side — is exempt, because the neutral can be fished later.
- • Switch loops in old work: a rewireable path is the test. If adding a neutral later means opening drywall, the neutral goes in now.
- • Using the equipment grounding conductor as a return path for an electronic switch is never permitted — that's exactly the practice this rule exists to kill.
404.9(B) — Switch & Faceplate Grounding
- • Snap switches and dimmers connect to the equipment grounding conductor; metal faceplates must end up grounded through the yoke.
- • Metal boxes with proper bonding satisfy this through the mounting screws to a self-grounding yoke; nonmetallic boxes need the EGC landed on the switch's green screw.
- • Replacement in an old box with no grounding means: GFCI protection or a nonmetallic faceplate arrangement is the permitted fallback.
- • Related: switches must be accessible, with the operating handle's center grip no higher than 6 ft 7 in. (404.8(A)).
Old-work switch box with no neutral and a smart-switch request?
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