In this diagram the incoming hot wire attaches to the first switchs common dark colored terminal. When wiring a 3 way switch first screw the terminal screws of the new switch until they are difficult to turn.

Tiny House Electrical Understanding The 3 Way Switch
How wire 3 way switch. Turn the power off at circuit breaker. The two switches appear to be connected by a 3 wire plus ground cable. Secure the white wire to the second wire with the same color using a wire nut. It does not matter to which terminal screw this wire is connected. Connect 3 wire cable in the first switch box. The black screw is the common which we identified in the steps above as the switch leg or hot power source.
You will see a black screw and two gold screws on the switch. When nothing is hooked up there is power in the 2 wire plus ground cable on the upstairs switch. The two hot wires of three wire cable connect to a pair of brass colored traveler terminals on each switch. 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. Connect the ground wire to the green screw. The red insulated wire connects to either one of the 2 unused terminal screws shown in the image above to be on the top left and right sides of both 3 way switches.
Install the correct electrical boxes. Step 2 connect the black wire to the input 1 of your 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. This 3 way switch wiring diagram shows how to wire the switches and the light when the power is coming to the light switch. Strip all three wires with wire strippers. Connect the two remaining traveler wires to the two brass or light colored screws.
How to wire 3 way light switch step by step step 1. The first step in any electrical project is to make sure there is no. Take your three way switch. 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. Step 1 the breaker phase black wire neutral white wire as well as the ground green wire must be landed in the first switch enclosure.
Before you can install your new three way switch youll need to put an. The 3 wire cable enters through the top of the first switch box.