DIY Chatroom Home Improvement Forum

DIY Chatroom Home Improvement Forum (
-   Electrical (
-   -   Replacing 3-way switches - what is this extra wire? (

Proulx06 09-24-2007 10:47 PM

Replacing 3-way switches - what is this extra wire?
I love it when I decide to start projects at 11pm :furious:

Anyways, this is in our living room, replacing two three-way switches. I found the common wire on the first box, started removing the old switch when I realized there were five wires in the back of the old switch. Three black, one red, and the ground. The red looked to be one of the travelers, while the rogue fifth wire (a black one) was not tied around a terminal, but rather inserted directly into the back of the switch (through those holes - forgive my tiny electrical vocab). So I made the mistake of undoing everything, and now I'm not sure how to get it back. I've done three-ways before, but never have I had an 'extra' wire.

To add to my issue, each box has one wire that barely reaches the surface of the drywall, making it near impossible to screw into the new switch. Is there any way to lengthen this (maybe solder in an extension?)

Thanks all...hoping I can figure this out tomorrow and not have to call in a pro...

Stubbie 09-24-2007 11:46 PM

Is your wiring in conduit? If so post back. If cable read on.

Go to the other three way and tell me what is in that box as far as wire colors and cables. In terms of cables how many cables come into the box? By this I mean Romex type cables.... like one cable has a red, white, black and ground and one cable has a black and white, and ground so i have one 3 wire with ground cable and one 2 wire cable with ground. If you cant tell the colors then just tell me the wire count in each cable. You don't have to include the ground just say all the cables have a grounding wire.

Do this for both boxes and post what you find.

5 wires in the switch box is the correct number of wires for a typical 3-way switch circuit discounting the ground but two of the wires need to be white wires or at least they need to be neutrals in a wire nut together. Like this...

Is the wire your calling ground a bare wire and you only have one ground wire?

Do you know which box has the incoming power? You say you found the common in the first box but is it switched power or constant incoming power?

You're sure all the wires were connected to the switch? If so then incoming power is not located in this box.

I can tell you how to deal with the short wires....first lets solve the wiring.

Please answer the questions asked


Proulx06 09-25-2007 10:03 AM

I'm at work now, but I read your post this morning and took a look at both boxes before I left. I'll try to explain this best I can.

First off, it probably is worth noting that these switches do not control a light - rather, they control the top plug in all the electrical outlets in the room, to which we have lights plugged in. So that might change things.

Next, here are the wires in each box:

Box 1:
Black (the hot wire when the power is turned on, thus the common, right?)
Red (the short one that barely pokes out of the box

Box 2:

I have a feeling it has to do with the outlets. Like, for that first box, you'd have one common (the hot wire), two travelers, and the wire that runs power to the BOTTOM plug in the outlets. Thus, that one would have to be joined in with the hot wire. Is this a correct assumption?

Thanks so much for your help, I really appreciate it.

Stubbie 09-25-2007 10:37 AM

Yes this makes a big difference. I have to leave for about 4 or 5 hours I think your probably on the right track with the two blacks on the common idea. Maybe one of the other guys can solve this while I'm out, if not I have a pretty good idea whats going on. So will post back when I get the chance this afternoon. Power is coming from a receptacle I'm pretty sure as there doesn't appear to be a neutral in either switch box.


Proulx06 09-25-2007 10:45 AM

Great, thanks, I'll give that another shot tonight. Can anyone help with the short wires? I'd like some extra room to work with given the difficulty already.

Stubbie 09-25-2007 10:47 AM

Are you dealing with solid copper wire or stranded I have a few minutes... sorry gotta go

If solid go to lowes or home depot and get these push connectors and add them to the short piece then add a pigtail.

If stranded you need a push connector called Wago brand. The others are for solid only for wire 14 awg and up.

No way for a wire nut to get a pigtail from that?

J. V. 09-25-2007 11:20 AM

As simply as I can I will tell you how to connect a three way. I will not tell you how it works, okay? Looking at Stubbies drawing.

One switch gets the hot wire connected to the "black terminal".

The travelers go from one switch to the other "no breaks" to the yellow terminals.

The second switch "black terminal" goes to the load (receptacle) or light.

The neutral can be derived from any source in the circuit. It does not have to be in the switch box.

Do you have a way to check continuity to verify what I have described?

That would be the best way to be certain you are connecting the right wires to the right terminals.
The extra wires you see are most likely for another circuit or in the same circuit to supply other loads.
It is apparent that the installer did not use 3 wire cable, as you would have had a red, black, white and ground in the switch box.

Take a good look at Stubbies drawing but do not concern yourself with the inner workings of the switch. Just the terminals.

ps....It doesn't hurt to get it wrong a time or two until you get it connected right. You might trip a breaker or it just will not work, but you CAN do it.....John

Oh....the short wire. Don't solder it. Use a wire nut or a butt splice with tape.

Proulx06 09-25-2007 12:21 PM

Great, thanks to both of you. It is copper wire, and I'll be stopping by HD to pick up a pair of those things and some extra red wire.

I think I understand what's going on - my issue now is, in that five-wire box, to determine which wires are the travelers and which one is the wire that goes to the bottom receptacle. I know the ground and I know the hot wire - the other three might have to be trial and error.

As for testing continuity to find the common wire in the second box, I do have a small radio shack multimeter, but I'm not sure it has the settings I need. I tried a few and I'm not sure any of them measure continuity.

scorrpio 09-25-2007 12:21 PM

There are a number of things coming to mind, and you would do well to check a few things.

First and foremost, with switches out and all wires disconnected, if power is on, are bottom outlets energized? Are they all energized, or some of them are completely out?

How are wires coming into the box? How are they grouped? Do you have each wire coming in through its own hole, or some apparently come within same BX/Romex sheath? How old is the wiring? Is it knob/tube? Are there ant white wires coming through the box?

Stubbie 09-25-2007 04:26 PM

Ok as others have said this can be wired a few different ways and may or may not take a few tries to get it right.

One question before we get started....Do you remember at all (besides the common hot wire in box #1) where any of the wires went at this point? You need to be 100% sure so we don't head off in the wrong direction. In other words do you still remember which black is the mysterious 5th wire? How about box #2 remember where any of those went? If not 100% sure then just say so and we will go from there.

Btw the short RED wire in Box 1 is a traveler to switch box #2 but we don't know which red it is in Box #2.

And the black in switch box #2 is a traveler between switch boxes but we don't know which black it is in switch box #1

And we know the constant hot is in switch box #1

If you know the mysterious 5th wire that was connected to the back stab of the common of the switch in box 1 then we can make all the connections correctly in Switch box #1 before we start in switch box #2.

If you have a voltage tester that will speed things up a tad but it isn't necessary.


joed 09-25-2007 06:02 PM

This is probably the box with the power feed. The extra black wire is the feed to another part of the circuit that is not switched. Both of the black wire probably go to the common terminal.

Stubbie 09-25-2007 07:23 PM

Hi Joe

I'm glad you showed up .....your probably the best I've ever seen on any forum at figuring stuff like this out. So be sure to give your opinion on how to approach this..

My thinking is to go to switch box two and get the switched hot figured out (one of the reds) after we make the connections in box#1 and then I believe we will have it. I agree that mystery wire is just onward power.

This is of course if we have the incoming power figured correctly. I think we do though. Other wise there is something else switched out of #1 and power is in #2.


Proulx06 09-25-2007 07:38 PM

Thanks all for your dedication in helping me figure this out. I've just gone and removed both switches and turned the power on. I'm 100% certain that I only have one hot wire coming into box #1 (the box with the extra wire). In addition, the bottom receptacles in the entire living DO NOT work with the power turned on. Thus, I think you're all right, that the fifth wire is power for the bottom receptacle for the rest of the room and is not switched.

Stubbie, I do not recall, at this point, where the wires went. Noob mistake, and one I usually don't make (I *have* done this before, believe it or not :) ) So I'm going to take what I know and try it a few more times right now.

One thing that was mentioned was finding out which wire in box #2 is the common wire - I read something about testing for continuity. I have this unit from radio shack -

Will that do what I need?

Proulx06 09-25-2007 08:00 PM

Update - this is what I did to find the "extra" wire - the one that runs to the bottom receptacles.

I screwed the hot wire AND one of the black wires to the common screw in box #1. I then grounded the switch. Then I turned the power back on, and all the bottom receptacles worked regardless of switch position. So screwing in that extra wire in with the hot wire powered the bottom receptacles.

So now we know:

Box 1 - hot wire
Box 2 - extra wire to bottom receptacles

Just a matter of screwing in the travelers, then messing around with box #2 to figure out which is which, right? I'm still looking around online to find out how to find the other end of the common wire.

Stubbie 09-25-2007 08:20 PM

I don't think we need to fool with continuity but it would solve this also if we choose to.

What I would like for you to do is turn power off and connect that hot wire to the common of switch #1. Then connect the red in box #1 to one of the traveler screws. Nothing more . Get all the other wires and cap them or seperate them where they can't touch each other you can hook up the ground if you like and would be a good idea for safety.

Now go to switch box #2 and separate all the wires from each other. Turn the power on. Take your volt meter and find which red wire is the traveler. You may have to toggle the switch one time to make the distinction. It will have power on it in one of the #1 switch positions. If neither red wire is hot then test the black. I'm sure though it is one of the reds. Now turn power off again and connect the the red traveler to switch#2. Take the other red and connect it to the common screw of switch #2. Black to the traveler screw. Go to switch box #1 and connect one of the remaining blacks to the unoccupied traveler screw.

See if you can turn your switched receptacles on and off from both switches. If not switch with the other black then stick the one you removed in the back stab hole with the other common black wire.

that is how I believe this has been wired


All times are GMT -5. The time now is 09:26 AM.

vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
User Alert System provided by Advanced User Tagging (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.

Search Engine Friendly URLs by vBSEO 3.6.1