3way switch wiring diagram with power in and switched leg in the same box

CrealBilly

New User
Jeff
Someone will thank me for this, eventually.

Screenshot_20210113-205317~4.png
 

CrealBilly

New User
Jeff
You can use two wire for the travelers also. Old electricians trick

For this conversation and using existing (12-2 or 14-2 with ground) single switch wiring. You'll need a new length of 12-3 or 14-3 with ground. Run it to the new or existing box, wire as shown and install 2x 3way switches and a single wire nut and your in business.

Don't forget to tape the white wire with length of black electrical tape.so the next guy knows it's hot! I perfer to mark the white wire with a black sharpie myself.
 
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Oka

Casey
Corporate Member
Neither of the 12-2 or 14-2 are code, running and extra wire would require the lone wire to be taped to the romex that powers the 3way. In either case most cites and counties would not pass it, it will work and actually really not a big deal, except to the inspectors.

The House I bought the previous owner was into both electronics and electrical, so this house has 4 - 4way and 4- 3way switches wired in it... God only knows why
 

McRabbet

Rob
Corporate Member
Jeff, thanks for showing your diagram, which illustrates one of the more common situations where 3-way switches are added. When I wired my shop 15 years ago, I verified the wiring I needed by seeking good diagrams like the one you showed. There are many scenarios that are possible depending on where the source of power enters and if the user wants to have other elements such as receptacles or dimmer switches included. Here is a link to several scenarios where these options are diagrammed.
 

junquecol

Bruce
Senior User
For this conversation and using existing (12-2 or 14-2 with ground) single switch wiring. You'll need a new length of 12-3 or 14-3 with ground. Run it to the new or existing box, wire as shown and install 2x 3way switches and a single wire nut and your in business.

Don't forget to tape the white wire with length of black electrical tape.so the next guy knows it's hot! I perfer to mark the white wire with a black sharpie myself.
To use only two wire for traveler, you start at light fixture box. Run "hot" to first switch, connecting hot to switch and making up grounds. Wire nut and tape off neutral (white) wire. Using both white (with label) and black along with ground connect to other switch . From second switch, run hot back to controlled fixture. Two wire is a LOT less expensive than three wire. This is especially important when you have multiple two way switches in a circuit.
 

Alan in Little Washington

Alan Schaffter
Corporate Member
With just one diagram like this, you can often figure out all other configurations, e.g. P - SW - L - SW, P - L - SW - SW, and P - SW - SW - L, etc. by just virtually/visually moving the light fixture along the wiring to its desired location in the circuit.
 

marinosr

Richard
Corporate Member
To use only two wire for traveler, you start at light fixture box. Run "hot" to first switch, connecting hot to switch and making up grounds. Wire nut and tape off neutral (white) wire. Using both white (with label) and black along with ground connect to other switch . From second switch, run hot back to controlled fixture. Two wire is a LOT less expensive than three wire. This is especially important when you have multiple two way switches in a circuit.

I think as of the 2011 NEC all switch boxes must have a neutral. So while this was once allowed, it no longer is. Same reason why "California style" switches are no longer allowed.
 

CrealBilly

New User
Jeff
Jeff, thanks for showing your diagram, which illustrates one of the more common situations where 3-way switches are added. When I wired my shop 15 years ago, I verified the wiring I needed by seeking good diagrams like the one you showed. There are many scenarios that are possible depending on where the source of power enters and if the user wants to have other elements such as receptacles or dimmer switches included. Here is a link to several scenarios where these options are diagrammed.

Thanks for that link :)
 

CrealBilly

New User
Jeff
Neither of the 12-2 or 14-2 are code, running and extra wire would require the lone wire to be taped to the romex that powers the 3way. In either case most cites and counties would not pass it, it will work and actually really not a big deal, except to the inspectors.

The House I bought the previous owner was into both electronics and electrical, so this house has 4 - 4way and 4- 3way switches wired in it... God only knows why

What do you mean by "Neither of the 12-2 or 14-2 are code" is that a mistake? Or do you mean in addition to an existing 12-2 or 14-2 for 3-way switch wiring conversation?
 
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Rkadish

New User
Rkadish
thank you, I replaced a 4 way switch but it was not setup the same as the one I took out. now I have to have one switch on for the others to work. not hard to figure out but the CB is down stairs and the switch is up stairs.
 

Dee2

Board of Directors, Vice President
Gene
Staff member
Corporate Member
When we started reno in the SC house we had a 3-way with 3 lights on it.
Switch 1 up, switch 2 down, 2 lights on
Switch 1 up, switch 2 up, all lights off.
Switch 2 down, switch 1down, 3 lights on.
We've since rewired it.
 

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