Three wire cable runs between the switches and 2 wire cable runs to the light. When wiring a 3 way switch circuit we will be using a 3 wire cable known as romex coming from the source such as the breaker box.
3 Way Switch Wiring Diagram House Electrical Wiring Diagram
3 way switch wiring. Take a closer look at a 3 way switch wiring diagram. The two switches appear to be connected by a 3 wire plus ground cable. Connect the wire marked common to the black or dark colored screw. When nothing is hooked up there is power in the 2 wire plus ground cable on the upstairs switch. Then a 4 wire cable going between the two 3 way switches and then a 3 wire cable going from the switches to the load. Typical 3 way switch wiring nm cable.
If you are trying to troubleshoot a 3 way switch operation then you will need to identify the function of each wire. When wiring a 3 way switch first screw the terminal screws of the new switch until they are difficult to turn. 3 way switch wiring diagram. In this diagram the incoming hot wire attaches to the first switchs common dark colored terminal. Connect the two remaining traveler wires to the two brass or light colored screws. 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 black and red wires between sw1 and sw2 are connected to the traveler terminals. The two hot wires of three wire cable connect to a pair of brass colored traveler terminals on each switch. Pick the diagram that is most like the scenario you are in and see if you can wire your switch. 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. Wires consisting of a line a load a neutral a pair of travelers and two 3 way switches. The black line wire connects to the common terminal of the first 3 way switch.
With these diagrams below it will take the guess work out of wiring. Traveler wires are interchangeable on each switch. A 3 wire nm connects the traveler terminals of the first and second 3 way switch together. All three way switch and 2 way switch wiring diagrams have the same basic components. Connect the ground wire to the green screw. In the 1st diagram below a 2 wire nm cable supplies power from the panel to the first switch box.
This might seem intimidating but it does not have to be. This 3 way switch wiring diagram shows how to wire the switches and the light when the power is coming to the light switch.
Gallery of 3 Way Switch Wiring
