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I have a two-year-old home with an unfinished basement that I wanted to add a few recessed LED lights to an existing run of four traditional light bulb fixtures.
When I completed the wiring and flipped the breaker, the lights work fine, but now the switches don't turn the lights off.

The original run was 14-2 from power to light fixture, 14-3 from that light to another light fixture and split of 14-2 to lower switch and 14-2 to the next light with two additional lights before terminating at the top of stairs switch. The lower switch has a 14-2 and a 14-3 running out of it.

In the new run, I removed the 14-3 between the two lights but did not change the original wiring from the box to the first fixture or the wiring from the switch to the middle of the run. Basically, my four lights replaced the first two in the run. I'm not sure why there was 14-3 just between two lights at the start of the run.

Also, I did tie the 4th light into just one of the lights in the middle so not in series, but not sure if that is the issue or the 14-3.

I do have a book on wiring but didn't see my particular problem in the discussion on 3-way switches. I truly appreciate any help. Thanks.
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    For anyone puzzled by the term "3-way" it's what the rest of us would call a 2-way ;) See en.wikipedia.org/wiki/…
    – Tetsujin
    Feb 15 at 12:38
  • I added links to the lower switch, which I did not modify, and the first junction between the switch and lights. This previously had 14-3 running to it. Feb 15 at 13:27
  • I'm confused by the part where you "removed the 14-3 between the two lights ...". Surely all 3 wires (+ ground) were connected to something at each end of that 14-3 ... ? What are those things connected to now?
    – brhans
    Feb 15 at 20:32
  • The 14-3 were connected to single-bulb fixtures. I am no longer using those fixtures, except one as a junction box right now in the picture. I'll try to draw it out and post that pic. Feb 15 at 21:17
  • Added a sketch of the setup. Hopefully that helps visualize what I'm talking about Feb 15 at 21:40
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OK, I notice that in the "junction" box, you have matched up all black wires and all white wires. As if you expected that all wires just come naturally color-coded like that. No, that does not happen, unless you do it yourself.

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Designing a 3-way+lamp complex is not that hard. Certain wires have to go certain places, and they have conventional color codes. But the wires don't come that way by default, so you must forcibly "take over" the wire colors by remarking.

And by "must" I mean for the sake of doing sure, steady and efficient work when you are a novice. Code doesn't actually require re-marking, unless the wire is white.

Further, the topology of the cables must be "Tree" or "Vine". It cannot ever be "Loop". For instance your drawing shows a 14-2 running from the light to the upstairs switch. Nosirree, can't do it.

The 3-way rules (and conventional colors)

You can take a blank sheet of paper, draw the boxes, draw cable routes connecting them, and then add the wires to this diagram as needed. Draw each one:

  • two (2) Travelers YELLOW must connect all switches, in string fashion. 2 wires here. There's no need to distinguish one from the other, so they are both yellow. They go on the brass screws of 3-ways.*

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  • Always-hot BLACK must connect the power source with one of the 3-way switch "commons".

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  • Switched-hot RED must connect the other 3-way switch "common" with all of the lamps.

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  • Neutral WHITE must connect the power source with all of the lamps. Switches installed or wired post-NEC 2011 also need neutral wired to one switch (see dashed line here), that's for smart switches.

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So draw all that out. Once you do this, it will become perfectly apparent which cables need how many wires, and how to remark them so they are colred by function. You can also see what went wrong in your junction box.

Most of the time it will work out "nice and neat" in the sense that no cable will need more than three wires.

Sometimes, you get into a jam where you need 4 or 5 wires in a cable. (for instance, if we were trying to deliver switched-hot (RED) and neutral (WHITE) to the upper right lamp via the 3-way switch cable, we'd need 5 wires - whoopsadaisy!) The solution is to rearrange the cable topology so the 3-way switches are a "spur line" - a branch that contains all the switches and only switches. This sometimes means running a /3 alongside a /2, but them's the breaks. I believe your setup came to you that way. The wires up the spur need to all be /3 cable (the first segment to bring neutral to a 3-way, and the other segment for 2 travelers and a common).

Other times you'll get a happy accident where you need black, red, white and by golly, that's what's in the cable!

When you build it for real, use the tape to mark the wires. Believe me, you'll thank me next year when you're trying to troubleshoot it.

Marking rules for white wires.

A wire which didn't start hot can never be re-marked to white. However white can be reused as a hot wire if neutral is not present, but there's a pecking order to it.

  • White must be neutral if neutral is in the cable.
  • Otherwise, if always-hot (black) is in the cable, white must be always-hot. Often you have a black-white cable and you need black-red, and you can't mark the white to red, you must mark the white to black and the black to red.
  • White can never, ever be switched-hot (red).
  • If you have 2 travelers and always-hot, white must be always-hot (and must be marked).
  • If you have 2 travelers and switched-hot, white must be a traveler (and be marked).
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  • I've added a sketch to the original post which shows what I think I need to do, but I'm confused by the junction box connections. Should Red and Black be joined? Feb 17 at 19:08
  • @Tom correct, except you must put /3 (black red white) in between the Junction Box and the first switch, if that is readily accessible. You don't join any two wires, but I very strongly recommend you remark the wires with tape so the wire color indicates wire function. That way you are always joining same-color wires. It takes $5 for tape and a few more brain cells than "paint by numbers", but "paint by numbers" only works if you have a Web diagram to crib off of, and in something this custom, you never will. Feb 17 at 19:33
  • That's the weird part. The original run only had a 14-2 coming out of the switch to the light/junction. You can see it in the metal box. If I run the 14-3 from the junction to the switch, I assume the red connects to red at the junction and to the red traveler on the switch? Thanks again for the help. I'm mechanically minded, but this electrical stuff is messing with me. Feb 17 at 20:29
  • @TomEhrhart I know, right? I find this stuff maddeningly confusing too, and that is why I use colored tape. I don't know how people like you can stand just leaving the wires at the default colors and having to remember "in this box black from this cable goes to red from this cable"... I can't do that, I know my limits. Anyway yes, when you run 14/3 from junction to switch, the white is unused, until the happy day you get a motion sensor or smart switch. The 3 wires are always-hot, switched-hot, and neutral (remark them black, red, white - oh wait, they already are!) Feb 18 at 18:23
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    Ok, figured it out. In connecting to the switch that previously only had 14-2 running into it from the lights, black went to common and white went to white of the 14-3 between the switches. In the new 14-3 I had connected the red to the red common. Once I removed that all works as it should. Thanks for all the help! Feb 20 at 18:31

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