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I have a 3 way switch with Source at First Switch and Light Between (same as below diagram)

enter image description here

I opened light fixture to pained the wall and after putting the light it did not work. I have tried following the wiring diagram but still does not work.

To ensure if my light fixture is good - when i plug it it outlet then it turns on.

To troubleshoot I even took out light fixture and tried attaching to source hot and neutral wire but light still does not work. when checking hot wire with multimeter it shows 122 volts with ground but show 0 with neutral wire.

I am not sure what I am missing and where to start as when direct connection of light fixture with source wire does not work then hooking up switches is also not working as expected.

Can someone help diagnose this? Its been like this since last few weeks me being little lazy.

Any help is appreciated.

The wiring diagram at the top of this page belongs to do-it-yourself-help.com. The original can be found here: https://www.do-it-yourself-help.com/3_way_switch_wiring.html

Adding picture of boxes : Switch1:Switch1 Light box:Light-box Switch2:Swtich2

  • Can you post photos of the insides of the boxes involved? – ThreePhaseEel Dec 31 '17 at 20:17
  • uploaded the box pictures – Ravinder Singh Dec 31 '17 at 20:31
  • Inyour first switch box, the one with the /2 cable coming into it. That cable must be the supply. If you wire the light directly to the /2, does it light there? – Harper Dec 31 '17 at 20:40
  • no, it does not light there. – Ravinder Singh Dec 31 '17 at 20:43
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    you should have taken the pictures before you disconnected anything – jsotola Dec 31 '17 at 23:32
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Here's your problem. Up in the light box, you don't know which of those /3 cables goes to switch box 1 vs switch box 2. So here's what I would do...

... after buying a multi-color 5-pack of electrical tape for about $3 because we are going to color-code everything: neutral=white... always-hot=black... switched-hot=red... travelers=yellow or some other color. There are always 2 travelers in a cable, they do the same thing, they are interchangeable, so code them the same color. "Two marked the same color" is pretty distinctive, as we are usually trying to make wires different colors.

Install 3-way switch #1.

  • Start by nutting the two white wires in box #1 to each other. Those are actual-neutral, and need no markings.
  • Note the /2 cable (the one without a red wire). That can only be supply. Its black wire goes to the COMMON terminal of the 3-way, this is the one with the black screw. Don't think about position, look at screw color.
  • Two wires remain, the red and black from the 3-way. Those will be travelers so tape them both yellow. These go onto the two brass screws on the 3-way.

We are done in this location, so you can reinstall the switch. Next: Figure out which cable is which up-top.

  • Cap off all the wires, and go to town with a voltage detector. If you find one cable is hot and the other is not, you are done with this section.
  • If you don't have a voltage detector, use the lamp as one. Shut off power, pick one cable and attach the lamp to its white and red wires.
  • If the switch makes the lamp turn on and off, you found cable #1.
  • If not, try the other cable.

Mark cable #1 and tape the black and red wires both yellow, since they are the other end of those wires you marked earlier. Always mark both ends of a wire the same. It's downhill from here. Turn the power off.


Let's think about the yet-undiscovered wires. There are two ends of /3 cables - one in the lamp box and one in switch #2. These can only be the opposite ends of the same cable.

Most people want their lamps connected to switched-hot, otherwise it defeats the purpose of switches. Switched-hot is red. We'll make the other two travelers. That's black and white. Mark both ends of the black and white wires with yellow tape.

Fit the 3-way in the far box, with both yellow travelers again going to the brass screws, and the common (red wire) going to the black screw. Do the work carefully, and we are done here. You can close up the box.


Back up in the lamp box, nut together as follows:

  • a yellow to a yellow (doesn't matter which**)
  • the other yellow to the other yellow
  • Neutral (the only white, thanks to our remarkings) to lamp neutral (white or sometimes blue)
  • Switched-hot (the only red) to lamp's black, red or brown (whichever).

Power up, test, should be done.


** Now if you have OCD, and want "both 3-ways down" to be lamp off like I do, and it isn't that way, then go up in the lamp box and swap yellows. Done.

  • really appreciate you providing detailed answer, but it seems problem is at the source - when i connect the lamp to the source black and white wire, lamp does not turn on. I guess I will need to call the electrician. – Ravinder Singh Jan 5 '18 at 15:13
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If you measured 122 volts from hot to ground but 0 volts from hot to neutral then the neutral path is broken somewhere between the circuit breaker box and the place where you made those measurements.

You may have to trace the fault toward the breaker box. Just keep measuring between hot and neutral.

If anyone has been doing construction or renovation in the building, they might have broken a wire inside the walls. Otherwise the break will be in a junction box.

In principle you have to know what loads are on any one breaker and how they are chained together, but this can be difficult to discover in a finished house. Look for outlets or lamps that are no longer working and repeat your test there.

Be especially careful if you need to look inside the breaker box. Don't put your fingers in there; most services boxes are pretty busy inside and you could brush against something hot. I sometimes use a dry wooden stick to wiggle wires around or move them aside so I can trace them.

Once you find a suspected bad connection, turn the power off before working on it.

  • i am checking hot to neutral in swtich1 using the source wire black and white and getting 0 reading in multimeter, there is not join in between. Also when i attach the light directly to these two light does not turn on. – Ravinder Singh Dec 31 '17 at 20:44
  • check the neutral at the breaker panel – jsotola Dec 31 '17 at 23:37
  • how do I trace the wire to breaker with drywalls? – Ravinder Singh Jan 1 '18 at 5:08

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