With a pair of 3 way switches either can make or break the connection that completes the circuit to the light.
Three way switch wiring power at light.
The hot from the power source connects to the common terminal of the first 3 way switch sw1 and the neutral is spiced through sb1 to the second 3 way switch sw2 via the 3 wire cable c2 that also carries the travelers that connect the two switches where it is spliced through sb2 to the neutral terminal of the light.
Here we have a single light controlled by 3 way switches.
In this light switch wiring diagram the power feed joins the circuit via the light fixture where a two wire cable c2 runs from the light to the first 3 way switch sw1 and a 3 wire cable c3 joins the two switches.
The correct wire must be connected to the common screw of a 3 way switch otherwise the switches will not control the light fixtures correctly.
The ground wire goes through both switch boxes and the ceiling light box and it is connected at all junctions except the light with a pigtail short piece of wire and wire connector.
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.
The existing 2 wire black and white romex can still be used to connect a 3 way switch 2 and the light fixture.
If your 3 way light switch 2 is connected between the power supply and the light fixture as is most common.
The following article explains how to perform three way switch wiring when the power source is at the fixture.
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Two three way switches control one light with the electric power coming through the first switch flowing to the second switch and then to the light fixture.
Wiring a 3 way light switch is certainly more complicated than that of the more common single pole switch but you can figure it out if you follow our 3 way switch wiring diagram.
This is only a wiring schematic and not the actual wiring method used for 3 way switch installations.
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.
Two very old three way switches.
Wiring a 3 way light switch.
Below is a simple 3 way schematic that can be applied to all three way electrical light switch connections.
Two very old three way switches are depicted in the photo above.