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I am trying to replace an old ceiling light fixture. The old chandelier could be turned on from three different places: a light switch near the door, one near the kitchen, and another at the top of the stairs.

In the ceiling junction box are 2 red, 2 white, 2 black and 1 ground wires.

The new light fixture only has two wires - both black. One is ribbed - which I am assuming is the "white" wire.

I have tried multiple combinations - and can only get the light switch near the kitchen to turn on the light.

Please help!

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    Can you post photos of the insides of the ceiling box and the switch boxes? – ThreePhaseEel Aug 14 '18 at 22:20
  • Is this house wired in the "old way" so that switches often have no neutral in the box? Or is it wired with a neutral in each switch box so that powered switches can be used? – Jim Stewart Aug 14 '18 at 23:21
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    closevoter I think you erred. – Harper Aug 15 '18 at 3:43
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This one's more than a little tricky. But let's start by reviewing how 3-way circuits work in the first place.

(And by the way, you didn't make life any easier on yourself by unhooking all the wirenuts in the box. The right way to do this is only unhook the 2 wires that were hooked to the old light, aside from ground.)

So here's a basic 3-way circuit. Now I am a huge fan of identifying wires by color. I use wires in conduit, so I get to do that. With black-white-red cable, you can accomplish the same thing by marking both ends of the wire with colored electrical tape. I strongly recommend labeling as you figure out the circuit, and then always thereafter.

enter image description here

  • Brown - supply always-hot
  • Gray - supply neutral
  • Yellow pair - messengers (they are interchangeable, so you don't need to distinguish them from each other) Alt traveler color: blue.
  • Orange - switched-hot - hot when light is desired to be on.

Note that between the 3-ways, is "/3" cable (3-wire) cable. This is to accommodate a special rule: In any cable or conduit, currents must be equal. If one of the travelers is taking power to the lamp, the power must return via the neutral in the same cable etc. That's why I drew it very thin with wires bunched.

This isn't your circuit, though. Yours is a little more complicated because with 3 control points, it must involve a 4-way switch (UK:3-way). But not that more complicated: take a look.

enter image description here

You can see I've moved the bulb, but it's just cosmetic; it doesn't really affect the circuit any. And the 4-way just goes mid-line along the two travelers - inputs 2 travelers, outputs 2 travelers. You can have as many 4-ways as you please, just like that. I made the second set of travelers blue, but shoot, it's not that complicated, you could just leave them yellow.

Now. Imagine the first 3-way (and the passthrough neutral) is in a box. Imagine the bulb and 2 yellow messengers passing through) are in another box. Imagine the 4-way (and passing through switched-hot) are in another box. That is exactly how your house is wired.

enter image description here

Physically, it'd look like this if we color-taped all the wires (a lot). Note that in the /3 cable, the underlying hard colors used in your house could be absolutely anything.

Though I cannot say whether the bulb is left or right of the 4-way -- as you can see from the drawing, it changes very little either way.

So now you have some detective work to do. Take apart your switches, but don't remove any wires :) Among your switches:

  • The 3-way switch with only one cable in the box is the remote (far-end) 3-way. The two wires on brass screws are the messengers, the other will surely be switched-hot.
  • Only travelers will go to the 4-way switch. That'll be two wires from one cable, and two wires from the other cable. All those are travelers. The remaining wire from each cable is "passthrough" either neutral or switched hot.
  • The other 3-way switch will have 2 cables (a /2 and a /3 cable) - the /2 cable will be power supply source. Again, the two wires on brass screws are the messengers and will go into the same cable. On the supply cable, black will be supply-hot and white will be supply-neutral.
  • Up in the lamp, 2 wires from each cable will be travelers. The remaining wires will be switched-hot and neutral.

It's also remotely possible that the power supply enters the 4-way box. Let me know if that's the case, it makes the drawing slightly different, but not shatteringly so.

  • So that's why Home Depot sells those colored rolls of electrical tape. I've always taped my 3 way travelers black, but have never installed a 4 way yet. Great info! – Gary Bak Aug 15 '18 at 11:50
  • @GaryBak Yes. They have 5-packs for $4 and stock all 10 colors in individual rolls. I have all 10 and also 10 colors of THHN. It's necessary given how many circuits I cram in conduit. – Harper Aug 15 '18 at 22:06
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The fact that you have 2 black, 2 red and 2 white wires in the ceiling box suggests that this was not wired in the standard way for three switches controlling a single light.

  1. Are two of these switches 3-way and one a 4-way?

  2. Does the line power enter in one of the switch boxes or in the ceiling box?

Three switches controlling one fixture, line power enters in one switch box

EDIT The other way the power can enter is through the ceiling box.

Line power entering in ceiling box

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    It doesn't do either one. The light is in the middle between the switches. – Harper Aug 15 '18 at 2:42
  • Picture source attribution? – Michael Karas Aug 15 '18 at 3:31
  • @MichaelKaras, the attribution is watermarked in the pictures. :-) – fixer1234 Aug 15 '18 at 23:28
  • The watermark is not suitable. Using a picture like that so obviously from some web page should have an attribution link in the answer by the picture. – Michael Karas Aug 16 '18 at 0:12
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Defidently a 3 way circuit with a 4 way switch. With having 2 red,2 black and 2 white suggests the light is in between a 3 way switch and the 4way switch. Typical connection is the 2 reds connected together and the remaining connection will look like a back feed connection where the neutral from the feed side goes to the light and the black from the other wire goes to the light. The remaining black and white get connected together. Reason being is one generally wants to see a black and white to connect to the light. The other wires are the travellers where power is switched from one traveller to the other by the earlier switches in the circuit. The last switch(3WAY) decides which traveller wire gets connected to the light. The old,old way of doing this is where the switching of the neutral in the same manor as indicated above thus bringing a constant hot to the fixture. This information hopefully Leeds you to getting it working.

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