Wiring Diagram - Adding Another Switch to a 2 Way and Intermediate Switched Lighting Circuit Student training aid for the connections required to wire a lighting circuit using the 3 plate loop-in method. Video explains the connection required when adding a fourth switch to a 2 way and intermediate lighting circuit. I explain the connection in the 2 way and intermediate switches that are in the circuit and then altered and added to. The circuit is wired in twin and CPC cables (twin and earth cabl