The circuit shows how to convert a one way switch setup to two way using the conversion method , a three core cable ( plus earth *) is wired between switches, existing wiring stays in place (some connection changes at original switch) just add the extra wires and connections.
Note resistor is necessary only to make simulation work properly DO NOT add resistor to actual lighting circuit although in reality there is resistance in cables anyway.
Ground connection only included for simulation to work *
* Proper earthing/grounding as per country's electrical regulations should be applied
CAUTION DANGEROUS VOLTAGES INVOLVED consult qualified electrician if unsure
