Insteon 3-Way Switch – Alternate Wiring

June, 2014

A quick note before we get started:  An Insteon switch is not the same as a traditional light switch.  It is used for home automation and requires other devices for remote control.  If you are seeking help to install a non-Insteon switch, this article is not for you.

I’ve successfully installed 33 Insteon wall switches in my home over the past few years.  I am an amateur electrician with no formal training, so the process has been a continual learning experience.  Recently, I came across a wiring scenario that I had not seen before involving a 3-Way switch (2 switches controlling a single load).  After a bit of trial-and-error, I figured it out, so I wanted to document the wiring in hopes it will help someone else in the future.  I’m going to assume that anyone attempting this installation knows what they are doing, so I’ll skip the typical safety lecture.  Also, I’ll add my standard disclaimer that I’m not responsible for anything you do with this information.

Insteon provides the following wiring diagram for installing a 3-way switch (page 6 of the installation manual).  Note that this diagram is applicable for several different in-wall Insteon products including ToggleLinc (ON/OFF and dimmable), SwitchLinc (ON/OFF and Dimmable), Keypads and others.

3-way wiring

This diagram above assumes that the power line comes into the left wall box, a 4-wire cable connects the left and right wall boxes, and the load goes out the left wall box.  However, what about the situation when the load and electricity are wired to the same wall box?  This was the scenario I faced with my most recent installation.

The diagram below is the approach I used in order to get the Insteon devices to work in a 3-way configuration where the load and power come in to the same wall box.

3-way wiring (alt)

The main, subtle change in my diagram from the one Insteon provides is that the red traveler wire is used to pass the switched load power from the right wall box to the left wall box.

Some other comments:

  • I found it interesting that the Secondary (left) Insteon device does not actually do anything to directly switch the power.  In fact, after the initial installation, toggling the Secondary switch has no effect.  Only after pairing the two switches together can the Secondary switch affect the power flow by sending a signal to the Primary switch to adjust the load.  If the pairing data in the switches gets corrupted, the Secondary switch will lose the ability to switch the power.
  • I am a huge fan of Wago Wall-Nuts as an alternative to the twist-on wire nuts provided with the Insteon switch.  These are push-on nuts that make installation very fast and easy.  Insteon frustrates me at times because they seem to keep changing the wire gauge in their products, but I’ve always been able to make them work with the Wago products.  I bought a box of 100 a few years ago as I started installing the Insteon devices, and now I’ve nearly run out.
  • My electrician did a terrible job of labeling the breakers in my house.  So, as I’ve been systematically replacing switches with Insteon devices, I’ve been documenting the breaker that controls it.  This has saved me lots of time with other projects and allows me to avoid the trial-and-error effort involved with finding the correct breaker.


  1. Thanks for this info. I have the same issue. I tried your diagram, and I get no power to the switches? It’s weird because I have another switch powered on the same line and it is working fine. And when I use the switches elsewhere, they work fine. Any ideas?

  2. I am interested in installing an Insteon switch with a 3 way in my house. Do both switches need to be Insteon? Or can one switch be a standard 3 way? Is there a specific Model of Insteon switch that supports 3-way, or do they all support it? I havent found anywhere in the specs of the Insteon switches that mention 3-Way support.


      1. Thanks, but are there specific models of insteon switches I need for a three way switch, or will the standard insteon switches work as three way as well as two way?

      2. Can you not just keep the switch position (up/down) fixed at the primary and replace the switch at the secondary with an insteon switch wiring it with just the neutral and hot and the load capped?

  3. Really Insteon requires you to convert a three/four way switch system into a one way, then you use digital trickery (ie, pairing switches) to turn that 1 way into any number of ways.

    One piece of advice – label things before you start, so if you want to put your mechanical 3 way back in place, it’s easy to do.

  4. It would be simpler and not require the red traveler wire if in your proposal the left switch is the “master” and the right switch off on its own is the additional “software only” controller.

    In fact, all the additional controllers don’t even need to be wired into the same circuit, they just need AC power from somewhere.

    1. let me clarify. put the “primary” (“responder”) in the electrical box where the load is connected (left in your pic). “secondaries” (“controllers”) can go anywhere. In your diagram, you run white+black to the right box simply to give the “secondary” switch there its AC power, but you could also have run AC to it from another location.

  5. In your situation, why not just swap the Primary and Secondary? All you should have to ensure is that you have some source of hot in the box where the secondary lives. The Primary, as far as I can tell, is just the device that has the red wire attached to the load. All other devices don’t have the red wire attached to anything, and they communicate with the Primary via the “digital trickery” mentioned in prior comments. My only problem is that the LEDs on my Secondary devices don’t sync with the Primary unless that Secondary is used to make the change. That is, if I turn on the light from the Secondary, and turn it off from the Primary, the LEDs on the Secondary still show that the light is on. There is a little more here, but I’ll post a question elsewhere.

    1. I had that problem with a Keypad and a switch. I set up a scene so the keypad could control a light that had an Insteon switch. I found that, in the scene setup, I had to have both the switch and the keypad set up as both controllers and responders or when I would turn the light off with the switch, the keypad would still show it as on.

      Now I have to figure out how to make Alexa turn off the light and have it show on the keypad…

  6. For the connection I am attempting, the lights (Outside) I want to use with the Insteon switch are on the same circuit as another set of 3-way lights (Hall). The 2 sets share a switch box in the hall, and I have been unsuccessful at separating the 2 circuits. Each switch turns only one set of lights on and off, but all of the load neutral wires (4 – 2 for each load) are connected, and one black/red wire from each of the Power & Load wire sets are connected. For the Insteon lights (Outside), this switch box does not have the hot wire (it’s in the 2nd switch). For the Hall lights switch, the hot wire is in this switch box. I tried just connecting the wires for each set of lights, but then nothing worked. Any suggestions? (I can also send a diagram of the configuration). Thanks for any thoughts you may have.

    1. Red wires in boxes, in my experience, are almost never used with an Insteon installation. They allow traditional 3-way switches to work, but aren’t needed for Insteon. Your mileage may vary — they may be serving a necessary purpose in your case. That said, The process is typically gang all the white wires together, connect the always hot (black) wire to the black wire of the Insteon switch, and hook the black load wire (that goes to the light) to the red wire on the Insteon switch. In the box where there is no load wire, just hook up the switch to the white and (always hot) black. I put a wire nut cap on the red Insteon switch wire.

      Feel free to send a diagram; I’ll try to respond.

  7. I have a whole bunch of Insteon Micro’s, and a new house with quite a few 3-way installations. I’m contemplating whether I can use the traveler wire as the switch lead and only use one micro as the controller, for a savings of about $50 per circuit. A simple pushbutton at each wall location would toggle the light. Any thoughts?

  8. Had almost the same exact problem and without seeing your post I solved it the same way. The twist I had was there was no white wire between box 1 and box 2. Instead I had a black wire and two red wires. Luckily the boxes were just close enough that I could do a continuity check (without the use of an extension cord) to trace which was which. I labeled one a neutral so I could tie back to the neutral in box 1. Your diagram is excellent and would have saved me alot of time, wish I had found it earlier. Insteon should have this on their web site as an alternate wiring scheme.

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