3-way wiring question for dimmer - is Castera my only option?


I have a new build house that doesn’t seem to have neutral at one of the switch boxes. I mistakenly bought a Leviton HomeKit dimmer thinking I’d have neutral everyone.

I am trying to update a 3-way switch that controls 6 overhead LED can lights. I think I have line-switch-load-switch-1 (how can I tell)

Load/line is at one of of the gangways (neutral is in the back and capped) and there is a 3-way cable that the existing dump switch is connected to that’s red, white, and black. (The white does NOT have black tape)

What I presume is the slave gangway has only one 3-way cable coming in with red, white, and black that’s all connected to the switch (I think common + 2 travelers). There does not seem to be a neutral. I assume without fishing a neutral I need to swap to something like the Castera?

There is no way to re-wire my existing setup to work with the Leviton (which needs 2 travelers, neutral, and load)? Or can I hook one of the travelers to neutral and then use that on the other end of the 3-way to power the remote?

Look at these diagrams and see if they have one the fits your needs.


Thanks for the fast reply. I think it might be either the first or third scenario. Line/load in one gangbox. Is there a good way to tell the difference? I’m leaning towards the first because white is hooked up to the switch in the box with line.

Looking at the Leviton dimmers I think I need the black though. So I assume I keep that wired?

I intend on calling Leviton tomorrow.

In the US, most wire colors are not mandated, so people can and do use The different colors in different ways, especially if it’s near the end of the day and there’s only one spool left in the toolbox. So the first thing you need to do is use some tools to map the circuits so you know exactly what each wire does.

(Also, never try to wire a device in a way differently than the manual for that specific model describes. Different models are wired differently. If you don’t follow the diagrams for the specific model that you are installing, You can easily burn out your expensive new switch, or create a safety hazard.)

If you live near a Home Depot, many offer a free class on wiring a three way switch. It won’t usually cover smart switches, but you will learn how to use the tools and map the circuits in your house. And if you pick smart switches which are sold at Home Depot the instructor may also be able to get you some answers on those. So that’s a good place to start.

This forum is for people who are using the Samsung smartthings home automation platform. Since it’s a very active forum, it tends to come up near the top when you Google general home automation topics, but it is specific to that system.

Since you mentioned that you bought the HomeKit version of the Leviton switch and that switch is not compatible with SmartThings, do you have a smartthings hub?

If not, I’m afraid you’re going to get a lot of answers here that won’t apply to your situation.

If you do not have a smartthings hub and you are just looking for HomeKit solutions, then, yes, the Lutron Caseta line is going to be your best bet, and in fact may be your only choice at this point. Because the pico auxiliary is battery-operated (10 year battery), you don’t have to worry about any of the wiring at the auxiliary position. and they have several models of the master switches which do not require a neutral.

If you do have a smartthings hub, let us know which model and which country you are in and we can discuss other options.

Thanks for the reply. I was able to figure it out. When investigating it stumped me when the remote 3-way switch was hot when everything was unhooked. Come to find out it was just a 14/3 from the line/load box and the original electrician bridged the Black wire on this 14/3 directly to line and used the Red and White for travelers.

After calling Leviton, I put the matching dimmer into the one w/o Neutral. I then bridged over neutral on the white wire and used the other red traveler for YL/RD while keeping the black wire bridged to line.

On the box with line/load I hooked bridged into neutral, bridged the BK directly to line, connected YL/RD to the traveler (from the other switch), and tied RD to load. Seems to be working.

1 Like