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.
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.
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.