> >
>

# How to hook up a 3 way switch?

#1
04-25-03, 06:20 PM
fatty54usa
Visiting Guest
Posts: n/a
How to hook up a 3 way switch?

Ok i have done my fair share of wiring but i have never hooked up a 3 way switch. I have one light in my attic that is getting controlled by two switches but I am not sure on how to connect them. I have 14/2 wiring running to both. Any helpful hints...PLEASE!!!

#2
04-25-03, 06:39 PM
Member
Join Date: Sep 2000
Location: United States
Posts: 17,733
Received 1 Upvote on 1 Post
There are a number of different ways to wire 3-way switches. And you will need at least some 14/3 cable. The first thing to determine is where the power cable comes in. Here are five different ways to do it. I use a "=" for 14/3 and a "-" for 14/2.[list=1][*]Power-S1=S2-L1.[*]Power-S1=L1=S2.[*]Power-L1=S1 and L1=S2.[*]Power-L1-S1=S2.[*]Power-S1-L1 and S1=S2.[/list=1]Pick the cable routing best for your situation, let us know which one it is, and we can provide the connection details.

#3
04-25-03, 06:40 PM
texsparky
Visiting Guest
Posts: n/a

OK, here's a HINT

#4
04-25-03, 06:53 PM
Member
Join Date: Sep 2000
Location: United States
Posts: 17,733
Received 1 Upvote on 1 Post
Pretty good hint tex. That web site provides five wiring diagrams for the same five options I offered. Now we won't need to provide the connection details later.

#5
04-25-03, 07:09 PM
blasttapes
Visiting Guest
Posts: n/a
I may wish that I had made a diagram but, oh well, let's give it a shot verbally. 3 way switches have 3 screws (as opposed to the 2 screws on a standard switch). Look carefully at a 3-way switch- one of those screws is a different color than the other 2 (call it the odd screw, very important to note this!). Connect the odd screw of switch 1 to the light (black) and the odd screw of switch 2 to the hot power (black).

That leaves 2 screws left over and unconnected on each switch, doesn't it? Those are the transfer screws. Connect the transfer screws together from switch to switch. It doesn't matter which one goes to which one.

Finally, connect the white from hot power to the white of the light.

Now, clear your mind and look at it from another perspective. Picture a regular switch. Two screws. One screw goes to hot power and one screw goes to the light, right? Now, imagine breaking that switch in half and putting each 1/2 of the broken switch on the 2 areas that you wish to control that light from. The light is connected to one half and the power is connected to the other half. Now, imagine each half is a 3-way switch now. Connect the two transfer wires and you've got a 3-way circuit.

A regular 2-screw switch is either on, or off. But a 3-way switch is a toggle, toggling the odd screw between the 2 transfer screws.

In your case you say you have a 14/2 going to each switch. Great! Make one 14/2 from one switch go to the light and one 14/2 from the other switch go to hot power. THEN- You'll need a 14/2 BETWEEN the two switches for the two transfer wires. Mark those transfer wires with red tape so no one mistakes transfer wires with any other kind.

To summarize: Power on one switch, the light on the other, connect the two transfer wires and you're in business! Now, ask about 4-way switches!

Brian

#6
04-25-03, 08:48 PM
fatty54usa
Visiting Guest
Posts: n/a
ok i got all this, now you only need one switch with power or do both switches need power?(from main source)

#7
04-25-03, 09:05 PM
Member
Join Date: Sep 2000
Location: United States
Posts: 17,733
Received 1 Upvote on 1 Post
Power only feeds into one of the three boxes. It can be either switch box or the light box. If you have more questions, please tell us which of the five cabling options you have or will have. You said you had 14/2 going to each switch, but you didn't say where that 14/2 was coming from, nor where the power is.

#8
04-26-03, 06:56 AM
fatty54usa
Visiting Guest
Posts: n/a
sorry i will lay what i have here. I remodeling my attic. I have no walls to worry about. I am running all new electric. I have 14/2 runing up from the basement(the main box). I was running wires then realized i didn't know how to hook up a three way switch. I had already run 14/2 from the first light switch to the light and from the second light switch to the same light. Now i haven't determined where the power was going to run into but it seems like what you guys/girls wrote above was you only need power to one of the switchs. All i need to do is run another 14/2 line from the first switch to the second and use that as my "red line". If power only needs to go to one of them thats cool then i will attempt it! Let me know and THANKS

#9
04-26-03, 07:35 AM
Member
Join Date: Sep 2000
Location: United States
Posts: 17,733
Received 1 Upvote on 1 Post
I strongly recommend against trying to do this with all 14/2 cable. I very strongly suggest that you buy some 14/3 and select one of the five cable routings presented in my first post, and then follow the corresponding diagram that texsparky gave you the link to. This will require that you remove the existing 14/2 cables from one of the switches to the light. But I know of no code-compliant way to do this by adding a 14/2 cable between the switches, although I'm sure you could hack something together that way that would function.