10.2 Switches and Device Wiring (NEC Articles 404 & 400)

Find the Correct 2026 Article

A wall switch and a fused disconnect are both switches, but their installation rules now start in different places. Article 406, Part III covers general-use snap switches, dimmers and electronic control switches. Article 404 continues to cover other switching equipment. Starting with the device type prevents an old Article 404 citation from sending you to the wrong rule.

Connections and Neutral Availability

A normal lighting switch interrupts the ungrounded conductor. Opening only the neutral can leave the load energized relative to ground even when the light is off. Multiway switching must preserve the correct ungrounded path through the travelers; a grounding conductor is never a traveler or neutral.

Use 406.30 to determine where a grounded conductor must be available for a lighting control. Read the stated exceptions and the conditions for multiple switch locations before concluding that every box needs a neutral. An electronic control may need a neutral to power its electronics; follow its listing and installation instructions. A bare or green equipment grounding conductor is a fault-current path, not a substitute operating-current return.

Ratings and Grounding

Match the device to the circuit voltage and the kind of load it controls. A dimmer's incandescent rating does not establish its LED or motor rating. Check the marked rating, lamp compatibility and any derating required when devices share a box. A product marked 600 W is not evidence of a universal NEC maximum for all dimmers.

Ground switches and conductive faceplates by the permitted equipment-grounding means. For an old box without an EGC, apply the actual replacement-device conditions in the Code; do not create a neutral-to-ground jumper at the switch. The ordinary switch grounding rules and the replacement exceptions must be evaluated separately.

Flexible Cords: Permitted Purpose Matters

400.10 covers permitted uses; 400.12 covers uses that are not permitted. A cord may serve suitable portable equipment or another expressly permitted application. It does not become permanent building wiring merely because its conductor ampacity is adequate.

For example, a listed pendant luminaire can use a suitable pendant cord. Running an extension cord through a hole in a finished wall to supply a permanently installed load is a different use and is prohibited as a substitute for fixed wiring. For a cord-connected appliance, also check its equipment article and listing: permission for one appliance does not authorize every stationary appliance to use a cord.

Choose the cord type for the environment and protect it from strain and physical damage. Table 400.4 is the starting point for cord types; 400.5 addresses ampacity. Wet-location suitability, oil resistance and temperature ratings are product characteristics to verify, not assumptions based on jacket appearance.

Study references: 2026 wiring-device migration, by NEC CMP-18 chair Robert Fahey and Mike Holt’s 2026 volume 1 contents.