Light Switch Wiring Diagrams - Do-it-yourself-help The black loop wire is connected to the other terminal and at the light, to the hot terminal on the fixture. This is an updated version of the first arrangement. Because the electrical code as of the 2011 NEC update requires a neutral wire in most new switch boxes, How to Wire Lights on a Trailer | Wiring Diagrams Fortunately, almost all wires you need (except for a brake controller wire) connect to your vehicle’s tail light assembly. In this case, you will need a set of wiring taps and a pair of pliers. Trailer Wiring Diagram. To connect the electric system of your trailer to 5/5(2) How to Wire a 3 Way Switch - 3-Way Switch Diagram How to Wire a 3 Way Light Switch With 3-Way Wiring Diagram and Step By Step DIY Instructions. With Complete list of Required Material & Walk Through Video.5/5(7) How to Wire a 3 Way Light Switch | Buzzza Figure A: 3 Way Switch Wire Diagram—Power to Light Fixture. This three way light switch wiring diagram shows how to do the light switch wiring and the light when the power is coming to the light fixture. In this diagram, power enters the fixture box. The black hot wire connects to the far right switch’s common terminal.