Three Way Switch With Two Traveler Wires plus line and load

I have an existing three way setup using the TP Link wifi-three way switch. I’d like to convert it to the Honeywell Z-wave in-wall switch with an add-on but the wiring configuration does not seem to fit. The current setup involves two traveler wires (Red and Yellow) plus the line wired on the switch itself and the load and neutral pig-tailed to the switch’s neutral line. The second switch is wired the exact same way.

Trying to do the same setup with the Honeywell switch plus the add-on doesn’t look like it would be a viable solution as the add-on does not have space for the line wire.

I’m attaching a pic of how my current smart switch is wired. You can’t see it well in the pic, but there’s a black wire pig-tailed in with the neutral wire to the switch’s neutral wire. I’d appreciate any advice.


  1. Do you have the user manual for the TP Link switches. Would be helpful to know how they work in a 3-way setup
  2. Do you know where line and load wires are: in the same box or one in each?
  3. Are your Honeywell switches the ones made by Jasco?

For Honeywell/GE/Jasco switches that I’m familiar with, in a 3-way, only the primary is a Z-wave device. The “add on” is a special, dumb, remote that uses a traveler and neutral to communicate with the primary.

Hi Hal! Thanks for the reply.

  1. I’ve got it around here somewhere. I’ll dig it up.
  2. Same box for both switches.
  3. Yep.

I’ve got the Z-wave device plus an add-on. I just don’t see what I should do with line and load wires in the add-on box when the add-on switch doesn’t have spaces for them.

In order to help I will need clear pictures of both boxes so I can see the wires coming into each box, not just the add-on. As @HalD suggests a link or model number of your current switches will be useful to determine line, load, traveler, etc in your current switches.

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It’s not at all normal to have both line and load in both boxes for a 3-way. You’ll normally either have line in one with load in the other or line and load in one box.

Unless the TP Link switches were set up in some form of virtual 3-way. Or it’s possible something unusual had to be done to power the two TP Links.

Did you install those? If yes, was there a dumb 3-way there before.

With @ritchierich on this, it’ll get sorted out! Get pictures showing how the wires end up in cables in both boxes and the TP Link info.

I installed them, yes.

I assume that some aspect of the TP Link switches talk in order to stay in sync.

Attaching a picture of the second box in case that helps in the meantime.

I’m going to get some pics of the wiring as they go into the boxes, but that’ll be several hours.

Thanks for your help so far, everyone. I really do appreciate it.

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Model number is visible on that picture.

At a guess, you got this:

Yep. That’s the one.

Did my best to get pics of the wires as they sit in the boxes. If these still aren’t clear, I can undo the switches.

Box 1

Box 2

Ok, did a little reading on the TP Link HS210 switches including this FAQ

While I didn’t find an actual wiring diagram, it seems those switches are identical and are paired somehow, possibly via the traveler wire or possibly by the app.

The diagrams at the FAQ link above show how a typical dumb 3-way works.

  • The black wire in the cable coming from the breaker is attached to the black, common, terminal on a 3-way.
  • Two wires, usually red and black, from a cable running to the second switch are connected to the brass terminals. These are the travelers.
  • White wires from both of the above cables are wire-nutted together
  • In the second box, the red and black travelers coming from the first switch are connected to the brass terminals of the second switch
  • The black wire from a cable going to the load is connected to the black, common terminal of that switch
  • The white, neutral wires are wire-nutted together.

Do you think that’s what you started with before installing the TP Link switches?

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Pictures are better.

Looks like standard line in one box and load in the other. Each box has a 2-wire cable, one of those is coming from the breaker panel and one is going to the fixtures the switches are controlling.

The 3-wire cable is the traveler between the boxes. It looks like the black wire from that is being used for neutral while the red and white are the travelers.

I’m not sure how to tell from the pictures which box has line from the breaker and which has load.

If you’ve got a non-contact tester, turn power on and use the tester to check the line terminal of each switch. Unless I’m missing something, one and only one of them should have power no matter how the switches are flipped.

Agree with Hal here. One box has line from breaker and one has load to your light fixture. Unfortunately pictures aren’t enough for me to determine. You will need to use a multimeter to determine this. With light Off only one of the line/load screw terminals on your current switch will have power. Place one probe on that screw terminal and the other on the metal box(that’s your ground) to measure voltage. One will read ± 120 and the other much less and usually not zero.

That box will be the one with line from breaker. Please post back results and we can help you further.

One side issue. I’m not experienced with wiring without grounds.

I noticed that this is from the era when boxes were metal.

I think that the ground pigtail on the TP Links should have been attached to the boxes. And when you go to wire the new switches you should run a wire from their ground terminals to the box.

Is this correct, Michael?

With the light switch off, I get 120 from Box 2 and next to nothing from box 1.

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Ok, wait until @ritchierich checks my work but here’s what you need to do.

Box 2 will get the Honeywell smart switch, Box 1 will get the add-on. Black wires will be hot, white will be neutral, red will be traveler. Wiring diagram for this is with your add on switch.

  1. Turn power off at the breaker
  2. Remove both the TP Link switches, including removing the wire nuts

Starting at Box 1 with the add-on switch

  1. Connect the black wire from the 2-wire cable to the black wire from the 3-wire cable using a wire nut.
  2. Insert the white wires from both cables into the holes for the Neutral terminal on the add on switch.
  3. Insert the red wire into the Traveler terminal on the switch

In Box 2 with the smart switch

  1. Insert the white wires from both cables into the holes for the Neutral terminal on the smart switch
  2. Insert the black wire from the 2-wire cable into the Line terminal
  3. Insert the black wire from the 3-wire cable into the Load terminal
  4. Insert the red wire from the 3-wire cable into the Traveler terminal

I believe you should also attach the ground terminal of the switches to their box. You could use the wire pigtail that comes with the switches for this.

Done. Turn on power and test.

This is perfect! Exactly as I would have advised. Thanks @HalD

The correct answer following current NEC code is yes all switches need to be grounded. You should see a screw hole in back of box and you can purchase grounding wire pigtails at Lowes or Home Depot.

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Did as you instructed and it worked perfectly!

Thank you so much HalD and ritchierich for your help and advice. It feels great to have replaced those wifi switches and have gotten the Z-wave working.

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Happy to help when I can. It just happened that I had installed a GE dimmer and add on the day before you posted. :grinning:

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