A four way switch has an extra common screw to bring the total number of screws up to four.
3 way light switch power at switch.
Three way light switch with power feed via the light.
First run a 2 wire cable from the wall power to the black screw on 1 of the switches.
To wire a 3 way light switch you ll need 2 3 way light switches 2 2 wire non metallic cables 1 3 wire non metallic cable and 2 6 inch grounding wires.
The white wire from the switch connects to the black wire from the circuit power supply cable.
In a hallway or large room for example installing three way switches at both ends lets you turn the light fixture on or off from both locations.
Wall switches used to control ceiling light fixtures or other fixtures come in three types.
The most basic three way switch setup has two switches that connect and control one light fixture like switches on either end of a hallway staircase or large living area.
Four way circuits are just a tad different than three way circuits mostly since the light switch that you add in has to be a four way switch rather than just another three way switch.
For example a long hallway or stairway might use a pair of three way.
A three way wall switch is a common type of light switch that makes it possible to control a ceiling light or other electrical fixture from two different locations in a room.
Wiring a 3 way light switch.
With a pair of 3 way switches either can make or break the connection that completes the circuit to the light.
Most common is the single pole switch the type used to control a light fixture from a single location the next most common is the three way switch which is commonly used to control a light fixture from two different locations.
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.
1 circuit power supply cable 2 electrical box where the light fixture is mounted 3 4 these wires must be connected to the common screw 5 light fixture.
The hot source is spliced to the white wire which should be marked as.
Two common screws and two brass screws not counting the ground screw.
If your 3 way light switch 2 is connected between the power supply and the light fixture as is most.
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.