I am trying to replace the old switches in my 3 way switch setup. The old switches are

  1. Jasco ZW4005 smart switch
  2. Jasco ZW2004 addon switch. The existing switches

I replaced switch 1 which had 2 travelers, 1 common/ load wire which was normal.

But while replacing the switch 2 , I noticed that there is only 1 traveller wire and 1 load wire. The old switch was connected to only one traveller and one neutral, it was not connected to the load wire. I was surprised how the previous setup worked well.

In the new switch I connected one traveller to the traveller screw, load to the load screw and the switch powers up but it does not function as 3 way switch, both the switches work as normal switches independently.

The wires labelled, notice only one traveller wire

I am guessing the old switches had some support to handle this internally. Has anyone worked with these Jasco switches earlier? How can I enable the 3 way switch with only one traveller wire?

Edit: attached the image of setup suggested by using the old switches. How can i use new switch to make this work as a 3 way switch ? image of setup suggested on jasco site

  • 1
    Can you post photos looking into the backs of all boxes involved please? Commented Jul 3, 2022 at 5:48
  • The old switches were not connected to neutral at all. I realize you see a white wire, but wire colors are the "Twilight Zone" inside 3-way circuits. Commented Jul 3, 2022 at 6:30
  • "Jasco ZW2004 addon switch." has smart electronics in it to not need to be wired as a traditional 3-way switch. What brand/model switches are you replacing these with? What are the wiring diagrams provided by the manufacturer? Your diagram "as suggested by the old switches" is irrelevant as the new ones obviously work differently.
    – FreeMan
    Commented Jul 3, 2022 at 12:00
  • the one box you show has enough conductors, what is the other box?
    – Jasen
    Commented Jul 3, 2022 at 12:59

1 Answer 1


I do not have experience with these but looking at them, it's pretty obvious to me. One switch has terminals for line, load, traveler and neutral while the second switch has only traveler and neutral.

It must be that one is a master switch that directly switched line to load. The other is a remote-only switch that uses the "traveler" as power from the master and control signal to the master.

To replace these with normal 3-way switches, you need not only a second traveler, you also need a switched hot wire back from the remote position to the master position since the load wire is there.

Unless you have all of those wires or have conduit so you can easily pull new wires, you probably need to leave those switches there or replace them with similar.

Edit: while I was answering, you edited in the photo. I see that these is a "line/load" wire between the two boxes which, I assume, was unused in the previous setup. Unfortunately, as far as I can see, you're still missing a second traveler. I also see that it is using cable so it will be hard to add a wire.

This may allow you to use a larger verity of smart switches but you still cannot use standard 3-way switches.

  • I agree there are several models out there that function like this, the controller and the remote or master/slave some get upset with the later term, but there are multiple brands and styles that can be used to replace these the good thing is in the last 10 years the prices had come down,,, well prior to our current economic problems,
    – Ed Beal
    Commented Jul 3, 2022 at 6:56

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