3 Way Switch Wiring Diagram - Easy Take a closer look at a 3 way switch wiring diagram. Pick the diagram that is most like the scenario you are in and see if you can wire your switch! This might seem intimidating, but it does not have to be. With these diagrams below it will take the guess work out of wiring. Interested in How to Wire a 3 Way Switch - 3-Way Switch Diagram Regardless of what 3-way switch wiring diagram, you’re following, you’ll need to use a 3-wire cable to connect the two 3-way light switches. So what you should see if you have correct 3-wire electrical cable (Romex) is a black (power) white (neutral) and now a 3rd (Red) wire.5/5(7) how to wire a three way switch | Light wiring 2 way switch (3 wire system, new harmonised cable colours) 2 way switching (3 wire system, old cable colours) 2 way switching (two wire control) 3 way light switch using a two wire control; 3 way light switching (new cable colours) 3 way light switching (old cable colours) Before you start – Safety first; Light wiring diagram How to Wire a Light Switch - Diagram 1 - Ask-The-Electrician Easy to Understand Light Switch Wiring How to Wire a Light Switch - Diagram 1 . Summary: Easy to Understand Light Switch Wiring You are correct, when s new switch will not be used as a 3-way switch the Red wire is capped off with a small wire connector or electrical tape.