3 Way Switch Wiring Methods

 If the terms are new to you, 
go to the Key Page> http://s3switch.blogspot.com/p/key.html   
S3 is the blueprint symbol for 3 way switches.
 If you are trying to fix a 3 way circuit that is already wired but not working properly, 
go to the Fix Page> http://s3switch.blogspot.com/p/fix.html
 If you are about to install the wiring for a 3 way switch and you just want a basic method then use this most simple 3way switch wiring method "S3 Method #1" which is explained next:

       S3 Method #1     
The Basic 3way          
This is the best and easiest method of wiring 3ways. If you only learn one 
3way method, learn this one. 
6 important terms described on the 
Key Page  are shown here in red text.
Rating  Excellent A+  
The most simple and trouble free method. 
Level  Intermediate
Also called a "Plain Jane 3way" or "Power at one end switch leg at the other" 

Notes to the drawing above;

  • The green light is on in the Line Diagram. Current flows from L1 through the (purple) switch blade to the red traveler wire through the 2nd switch blade to the black switch leg through the light to the neutral.
  • The light is off in the Wiring Schematic because the second S3 (at the right) was flipped.
  • The white wire (dashed line) in the 14/3 is used as a neutral and the neutral goes directly to the light.
  • Notice that a hot and neutral are at the first 3way (at left) which could be tapped into to feed power to another nearby switch for a different light. This cannot be done at the 2nd 3way because the hot is switched and not energized all the time.
Compare the Wiring Schematic with the photo;

   ➣ A 2 wire (14/2, 12/2) feed is pulled from the nearest source of power, like a receptacle,
to the first 3way switch box. First, meaning the closest S3 to the power source.
   ➣ Next a 3 wire (14/3, 12/3) is run between switches from the first S3 to the second S3. This 3 wire is used for the travelers and the neutral.
   ➣ And finally a 2 wire switch leg is pulled from the second S3 to the nearest light and then to any other lights that are supposed to come on with these switches.
This is a basic 3 way switch wiring method. It is the best and easiest method of wiring 3 way switches. The switches are shown in a horizontal position to make it easier to visualize. In houses, switches should always be mounted vertically (up and down). The only items not visible in the image are the switch blades, shown as purple in the wiring schematic, but hidden inside the switches. The letter "C" in the photo identifies a special terminal called a  "common". Notice how the  "common" terminal at one 3 way has the black hot feed (L1) and the other 3 way's "common" has the black switch leg to the light. The other 4 switch terminals are the traveler terminals interconnected with red and black travelers. The cord plug on the left illustrates power (L1 + N). If you plugged this into a hot receptacle the switches would function properly to control the light. To simplify the image and make it easier for you to visualize, the ground wire is left out and the boxes were laid sideways. Also the 14/3 between 3ways is missing its white sheathing and the wires are normally inserted into the back of the box.

When switch wiring becomes confusing to you, repeat our switch wiring motto;
 From the hot, through the switches, to the light and back on the neutral. 

Which means that you are going to create a wiring pathway that will allow electricity to flow from the hot feed, labeled L1 in the photo, through all the switches (L1⇒C⇒red wire ⇒C) and then to the light's hot terminal and then connecting the light's neutral terminal (gold screw⇒bulb filament wire⇒silver screw) and back to the neutral, the neutral in the feed labeled N in the photo. (white wire⇒red wire nut⇒white wire⇒red wire nut⇒white wire⇒N) All this creates a circular circuit. 

If you have more than one light, you have a choice on where to connect your 2nd light. You can add additional lights by taping into the original light as shown here;

Or you can add additional lights by tapping into the switch leg at the switch as shown in the next method;

    S3 Method #1.1   
 A Basic 3way with 2 Switch Legs 
Rating  Excellent A+   
Level   Intermediate 
Also called a "Plain Jane 3way with 2 switch legs"
Description   Power at one end, 2 switch legs at the other. A 2nd light is connected to the switch leg at the switch instead of at the light.Notice that the black wires from lights connect to the common of the 2nd 3way. If they were connected to the first 3way's common the lights would not turn off because L1 is hot all the time. So when you're on a ladder pulling your 14/2 from the ceiling light down to your 3way, you have to run it to the 2nd 3way the one without L1.
But why run 2 switch legs to the switch instead from switch to light to light? 
Answer; to save wire. In the wiring methods above, the white wire, contained in the 14/3, was used as a neutral. In the next 2 methods the white wire will be used as a traveler wire not a neutral. Travelers carry the hot feed from 3way switch to 3way switch.

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