kwired
Electron manager
- Location
- NE Nebraska
A duplex receptacle is two receptacles, 15 amp duplex receptacle is therefore permitted to be only thing connected to a 20 amp branch circuit. 210.21(B)(1) says "a single receptacle installed on an individual branch circuit shall have an ampere rating not less than that of the branch circuit". Put any other load or receptacle on the circuit and this section no longer applies.
240.21 is the place to start for "tap" conductors. Subpart (B) is most commonly used and is for feeder taps. Subpart (A) is for branch circuits and sends you to 210.19 and 210.20. There you get some places where you can have a "tap conductor" like for cooking appliances, luminaires, etc. and typically with limited tap conductor length. It also sends you to 410.117 for luminaires which has a section giving you 6 feet of tap conductor allowed from an outlet box to a luminaire. Nothing in there allows for a reduced sized conductor (without additional overcurrent protection) for a switch leg.