enter image description hereenter image description hereenter image description hereI am trying to figure out how to install a 3-way switch. Unfortunately, I did not took any pictures of the previous 3-way switch installment, I thought this would be easy but after I bought the new switch, I saw it has different color wires and now I have no idea how to make this work. I have took picture of the exposing wires, as you can see, 2 blue and 1 orange. The new switch has 2 red, i black and 1 green. How should I connect this? Any advice? I also took a picture of the other ends switch. Not sure if this will help. Can anyone advise please?

  • Can you post a link to the other photo in a comment? Then somebody can edit it into the question.
    – Tester101
    Jun 22, 2016 at 14:51
  • Are you in North America? The switch looks like a NA 120v switch but I've never seen blue wires.
    – DoxyLover
    Jun 22, 2016 at 19:16
  • Can you get us photos of where the wiring to this box connects to? It'll either be the other switch for the light or the light itself.... Jun 22, 2016 at 22:47
  • 1
    That's not a 3-way switch. That's an electronic doozhickit of some sort, and it'll matter a lot which kind and how its instructions say to wire it. Protip: Disregard color. Color doesn't mean anything (except green is ground and white/gray are neutral, in North America). Jun 23, 2016 at 2:26
  • 1
    If you don't have a multimeter or other voltage tester, this may be of interest. Before poking around live stuff, I'd turn off the breaker and terminate all unconnected wires with a connector that has test ports ... like a Wago 221 or 222 or equivalents from Ideal and others. Then turn on breaker and probe the test ports to work out what is live when. Jun 23, 2016 at 9:18

2 Answers 2


This looks like a 3-way slide dimmer.

In the first picture it looks like there are five wires. Two black, two blue and one white(?). Is that correct? Can't tell what the white(s) is(are) connected to, if at all.

Just looking at the pictures(which are leaving out some needed information) and seeing that these are 4-square boxes, the box in the second picture has the travelers and switch-leg for whatever light is being controlled. Then the box in the first picture is most probably a feed in from the light box(common in older houses), a feed out to the nearest receptacle and the travelers going to the second box. Both boxes are probably junctioned somewhere, maybe in the attic or the light box itself.

Here's my take: if it is a feed in/feed out then there should be two white wires tied together in the first box. Black on the switch is the common, so it should be tied to either the paired blacks in the first box or the orange wire in the second. The red leads on the switch should be paired to blue wires in whichever box you're installing the switch(one red to one blue).

Again, this is only valid if what I saw in the pictures was correct. I'm including a few references just to help clarify.

enter image description here

enter image description here


Interesting colors... without a multimeter (I assume that's the case), the best answer is to use the light to test the connections. When wired correctly, the light should turn on and off at each switch (a switch should not need to be in one position for the other switch to work). The green wire should be the ground and it should be attached to the outlet box with a grounding screw.

Use a piece of tape and mark the wires (Red1, R2, Blue1, B2). Use the following possibilities (there are only 6 possibilities; check them off until you get the right order):

  1. Red1-Blue1, R2-B2, Blk-Org* chances are, it's this one
  2. Red1-Blue1, R2-Org, Blk-B2
  3. Red1-B2, R2-Blue1, Blk-Org
  4. Red1-B2, R2-Org, Blk-Blue1
  5. Red1-Org, R2-B2, Blk-Blue1
  6. Red1-Org, R2-Blue1, Blk-B2

Caution: You will need to turn off the breaker every time after checking- before wiring and rewiring.

Edit 1- Regarding a three way switch it is common to make the "common" screw or wire a different color than the other two traveler screws or wires. A green wire is almost always the ground. So I believe that the two red wires on the switch attach to the two blue wires in the box, and the black wire should attach to the orange wire in the box.

To gather a little more information, you could take the lamp out of the ceiling and see what color wire(s) are connected to the lamp. Again, my bet is that the wire connected to the lamp is orange. There will also be a neutral wire connected to the lamp.

If the ceiling wire is blue, or some other color, then you could use an ohmmeter to determine which wire in the box is connected to the lamp. The wire that is connected to the lamp is called the switch leg. However, at this point, it would be smarter to open the other switchbox (lets call it switchbox 2, and the switchbox in the picture will be switchbox 1), and take a look at the wires there. If you see the same color wire in switchbox 2 as is connected to the lamp, then you have likely found the switchleg (comming from switchbox 2).

Now, since you have both switchboxes open, the straight-forward approach is to test for continuity of the traveller wires. So you will need an ohmmeter to figure this out. Here's a video about checking for continuity: Continuity Test "How To".

To determine which wires are travellers, you need to first mark each wire (A, B, and C) in switchbox 2, and then connect two of the wires in switchbox 2 with a wirenut. Then go over to switchbox 1 and check for continuity between each of the wires.

Switch 2 ....................... Switch 1

Connect A and B ... Test continuity between Blue1 - B2, B2 - Org, and Blue1 - Org

Connect A and C ... Test continuity between Blue1 - B2, B2 - Org, and Blue1 - Org

Connect B and C ... Test continuity between Blue1 - B2, B2 - Org, and Blue1 - Org

Once you have found continuity, then you have found the two traveller wires. The third wire in the switchbox is either the hot/feeder or the switchleg. The hot/feeder and the switchleg connect to the "common" wire or screw of the three way switch. The traveller wires connect to the other screws or "leads" on the three way switches.

At this point you should be done, so (if you haven't done this already) make sure the lamp has been put back together. But since you have an ohmmeter, then you should also determine for certain which wire is the "common" wire (on the three way switch in the picture). Here is an instructional video: Testing your 3-Way Switch using an Ohm Meter

For extra credit-

To determine which wire in the box is the switchleg, you will need to disconnect the lamp from the switchleg and attach a long wire to the switchleg in the ceiling. Carry the other end of the long wire over to the switch box (whichever switchbox has the suspected switchleg), so that you can use an ohmmeter to check for continuity. If none of the wires are continuous with the switchleg in the ceiling (connected to the lamp), then you have either disconnected (and have been testing) the neutral wire, or the switchleg is comming from the other switchbox. Check for continuity of the other lamp-wire. After discovering which switchbox has the switchleg, then you know that the third wire in the other switchbox is a hot/feeder. The switchleg and/or hot/feeder needs to be connected to the "common" wire of the three way switch. Again, it is standard practice to make the "common" wire a different color (often black) than the two traveler wires.

Edit 2- Regarding the new picture that you added, it looks very much like the black wires in the wall (switch 1) are hot and the blue wires are travellers.

The switches being used are kind of unusual. I also see now (with the new picture) that one of the red wires is probably the "common" terminal, and the other red and black wire are the leads. If switch 1 is wired correctly, then (on switch 2) the red wire with a tag and the black wire are the travellers, which each attach to one of the blue wires, and the orange wire is the switch leg which attaches to the red wire (switch 2) without the tag.

enter image description here

  • 1
    Trial and error is not a good way to do electrical work.
    – Tester101
    Jun 22, 2016 at 19:03
  • 1
    @Tester101 People miswire three way switches all the time. I'm just saying, use the light to see if it's done correctly. Regarding this particular three way switch, where there are only 3 wires in the box, so he must have two travelers and a hot/feeder, or a switch leg. If he doesn't connect the hot correctly, the switches will not operate correctly- and since the other two wires are travellers, which are reversible, it's not an issue. Jun 22, 2016 at 19:20

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