First bend hook in the ground wire wrap around the green screw. Pick the diagram that is most like the scenario you are in and see if you can wire your switch.
Eaton 15 Amp 3 Way Toggle Switch Brown
Three way toggle switch wiring. Connect the wire marked common to the black or dark colored screw. There is only the single 3 wire plus ground in the downstairs switch box and only two 2 wire plus ground cables at the fixture. The two switches appear to be connected by a 3 wire plus ground cable. If you are trying to troubleshoot a 3 way switch operation then you will need to identify the function of each wire. We can number the tabs on the left from top to bottom 1 2 and 3. Wiring diagram 3 way switch with light at the end in this diagram the electrical source is at the first switch and the light is located at the end of the circuit.
This might seem intimidating but it does not have to be. Take your three way switch. Look at the bottom of the toggle switch and arrange it so there are three tabs on the left side and one tab on the right. When nothing is hooked up there is power in the 2 wire plus ground cable on the upstairs switch. The black and red wires between sw1 and sw2 are connected to the traveler terminals. 3 way switch wiring diagram.
All three way switch and 2 way switch wiring diagrams have the same basic components. Three wire cable runs between the switches and 2 wire cable runs to the light. Connect the two remaining traveler wires to the two brass or light colored screws. The two hot wires of three wire cable connect to a pair of brass colored traveler terminals on each switch. With these diagrams below it will take the guess work out of wiring. The black screw is the common which we identified in the steps above as the switch leg or hot power source.
Connect the ground wire to the green screw. Take a closer look at a 3 way switch wiring diagram. This 3 way switch wiring diagram shows how to wire the switches and the light when the power is coming to the light switch. Wires consisting of a line a load a neutral a pair of travelers and two 3 way switches. When wiring a 3 way switch first screw the terminal screws of the new switch until they are difficult to turn. In this diagram the incoming hot wire attaches to the first switchs common dark colored terminal.
You will see a black screw and two gold screws on the switch.

















