With these diagrams below it will take the guess work out of wiring. If you are replacing an existing 3 way switch.

Three Way Lights How Three Way Switches Work Howstuffworks
How does a 3 way switch work diagram. Sometimes a 3 way circuit doesnt work because someone tried to replace a defective switch and did not properly connect the wires. Take a closer look at a 3 way switch wiring diagram. Wiring a 3 way light switch. 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. 3 way switch wiring diagram. Wall switches used to control ceiling light fixtures or other fixtures come in three types.
The following method will address both problems at once. This might seem intimidating but it does not have to be. With a pair of 3 way switches either can make or break the connection that completes the circuit to the light. For example a long hallway or stairway might use a pair of three way. The three way switch is a variation of the standard single pole switch which controls a light only from one locationa third type is the four way switch which is used in conjunction with two three way switches to control lighting from more than two locationsthis configuration may be used in open plan homes or in large kitchens or great rooms where a central bank of lighting fixtures might. A three way light switch is different than a traditional single pole light switch as it contains an extra screw to connect an extra wire.
The second controls the light in the hall. Is it possible to connect 2 separate 3 way circuits to make a single 4 way circuit. Most common is the single pole switch the type used to control a light fixture from a single locationthe next most common is the three way switch which is commonly used to control a light fixture from two different locations. When replacing an existing 3 way switch take note of how the existing switch is wired before you remove the wiring then refer to your notes to help you wire the new 3 way dimmer switch. Pick the diagram that is most like the scenario you are in and see if you can wire your switch. Hi phil great article helps me understand how 3 and 4 way circuits work.
Many manufacturers are now producing dimmer switches that can be used for either single pole or 3 way switches. For more information on household ac current and grounding see how power distribution grids work you can see in the figure that the current runs through the switch. The white wire is neutral. Another dead giveaway of a three way switch is the absence of on and off markings. One 3 way circuit controls a light at the top of the stairs. This is known as the common screw and its usually black instead of brass or silver.
I have an older home with a stair way down to a hallway. Sometimes one of the switches has become defective. In this diagram the black wire is hot that is it carries the 120 volt ac current.