Det finns några problem med det andra diagrammet.
Först byter du den jordade (neutrala) ledaren. Detta är inte tillåtet, eftersom det skulle innebära att fixturen alltid är het.
National Electrical Code 2014
Chapter 4 Equipment for General Use
Article 404 Switches
I. Installation
404.2 Switch Connections.
(B) Grounded Conductors. Switches or circuit breakers shall not disconnect the grounded conductor of a circuit.
Exception: A switch or circuit breaker shall be permitted to disconnect a grounded circuit where all circuit conductors are disconnected simultaneously, or where the device is arranged so that the grounded conductor cannot be disconnected until all the ungrounded conductors of the circuit have been disconnected.
För det andra kör du inte alla kretsledare i samma kabel. Detta är inte tillåtet eftersom det kan leda till spökspänningar och oupptäckta fel.
National Electrical Code 2014
Chapter 3 Wiring Methods
Article 300 Wiring Methods and Materials
I. General
300.3 Conductors
(B) Conductors of the Same Circuit. All conductors of the same circuit and, where used, the grounded
conductor and all equipment-grounding conductors and bonding
conductors shall be contained within the same raceway, auxiliary
gutter, cable tray, cablebus assembly, trench, cable, or cord, unless
otherwise permitted in accordance with 300.3(B)(1) through (B)(4).
Se detta svar för mer information.