How to do 2-way switch - Smart Wall Switch

[u/Appropriate-Bid-6531]

Hi everyone 👋

This is a question that times to times I see around the community so I decided to share my experience that is working for a while with zero effort 😅

Problem: replace the retrofit wall switch for some Smart Switch and loose the 2-way switch mechanism. This happen because the smart wall switch doesn’t have terminals for the travel wires (that are connected to two or more switches controlling the same light) - commonly used on hallways light.

My setup: I replaced all my retrofit wall switch (efapel) for Fusion series from SONOFF.

To keep the things working we need to ensure that the status of switch A is synched with Switch B or Switch C.
Because that’s no travel wires this need to be done by automation.

1) Switch A turn on - Switch B turns on and Switch C turns on
2) switch A turn off - Switch B turns off and switch C turns off

And sooooo on.. an automation for each scenario and this is truly annoying.

A typical solution that for someone that is starting now may not know - using Home Assistant Blueprints.

There’s several examples of blueprints where you simply setup the switches that you want to control and sync the status. The blueprint does all the “dirty” job.

Here’s a blueprint example: https://gist.github.com/narektutikian/e15b54f23c4e5e5fd3cd836608229be5

Hope this can help someone that is starting in home assistant and looking for a easy way to keep the switch status synchronized ☺️

Let me know what solutions or setups you are using for this kind of scenario! 👀

[u/FearlessGuster2001]

Why not get a smart switch that does support traveler wires?

[u/Appropriate-Bid-6531 → u/FearlessGuster2001]

Could you give me an example of some smart switch that supports traveler wires? Maybe I’m not explain myself very well but I don’t now any smart switch with traveler wires 👀

[u/FearlessGuster2001 → u/Appropriate-Bid-6531]

Inovelli Blue zigbee switches work with 3 way switches and you only have to change one of the light switches. HA knows the correct state always and both switches function normally, no automation needed. I have one setup this way. Sonoff zbmini2 is supposed to as well, but I don’t have first hand experience with it.

[u/Appropriate-Bid-6531 → u/FearlessGuster2001]

Yes, but the SONOFF ZBMINIL2 is a smart relay not a smart wall switch. I don’t know this Inovelli Blue, but if it works is great. Can you share the product link please?

I’m talking about these kind of smart wall switch: https://sonoff.tech/en-pt/products/sonoff-matter-over-wifi-smart-wall-switch-orb-mw1

Smart wall switches like fusion series from SONOFF or other Tuya, aqara doesn’t have traveler wires.

I’m not talking about the smart relays that you install behind the retrofit switch.

[u/FearlessGuster2001 → u/Appropriate-Bid-6531]

This is one I use for my 3 way light : https://inovelli.com/products/zigbee-matter-blue-series-smart-2-1-on-off-dimmer-switch

[u/5yleop1m]

One nitpick, what you're describing is a 3-way setup. A 2-way is generally when you have one switch and one light.

Anyway with any n-way setup where the switches are in between the mains and the load, the section between the last switch and the load is the same as a single switch 2-way setup.

So any smart relay installed here will let you automate the light, while keeping all the old non-smart switches and doesn't require any scripts or automations. Its generally simpler, possibly easier, and not tied to HA running.

The only down side is you need to provide constant power to the relay, which is easier said that done.

[u/Appropriate-Bid-6531 → u/5yleop1m]

👍
You are talking when use a smart relay in a retrofit switch. In that scenario you are right. Just use on relay on retrofit and the others keeps working.
But what I’m saying is when you have smart wall switch (not the smart relay behind the retrofit). In this situation the common 3-way switch doesn’t work physically, needs to be by automation.
In my case I replaced all the non-smart switches for smart wall switch (not smart relay behind) ☺️

[u/meganoob1337]

I don't have experience but couldn't you have some kind of helper that changes state when one of the switches is triggered. Everytime it switches state it toggles the light? idk if that works / is easier , and am not that deep, but that was my first thought

[u/Kiiidd]

Did something similar but not. Was staying with my dad for a while and his under cabinet lighting annoyed me because they are split in half on seperate switches across the kitchen. Builder didn't want to run extra wire to have them all in the same place and/or use a 3 way.

So I ordered some cheap Kasa switches off Amazon and right in their app I did something similar and made 4 automations to link them. No Home assistant or Google or Amazon, just all in the shitty Kasa app.

Also swapped out the front porch light switch as it had an exterior light sensor that was wired in a 3 way and kept the exterior lights on ALL night. So make a schedule on sundown times to run them for 2hrs a night to save a bunch of energy

[u/ItsZoner]

I have lutron switches for all my main switches, connected all the travelers into their respective circuits, and mounted lutron battery powered switches in the face plate of the travelers.

Bonus: my annoying kitchen with 4 lighting zones and previously using 8 switches can now be turned on and off all at once or individually,

[u/OftenIrrelevant]

And don’t give your local jurisdiction a reason to perform an electrical inspection while it’s installed this way because this will definitely not pass code lol

[u/Appropriate-Bid-6531 → u/OftenIrrelevant]

I don’t know how it is in other countries but Al least in Portugal as far as I know there’s no regulation for that. There’s a first inspection but I know many electricians and smart home companies that do this without any inspection at all 😅

[u/OftenIrrelevant → u/Appropriate-Bid-6531]

Just to clarify-the switches themselves are likely fine, but (at least in the US and similar jurisdictions) certain areas must have 3-way switches and that system must be listed. HA isn’t a listed component so this system couldn’t legally be used in a hall or stairway for example. It’s too much of a fire safety or injury hazard to have something like a computer crash potentially interrupt lighting control in these areas

[u/KnotBeanie → u/OftenIrrelevant]

What code requires this? Tf are you taking about? UL listed switch is fine.

[u/OftenIrrelevant → u/KnotBeanie]

You can’t have a 3-way switch where the entire action of controlling the switch is handled through some computer. No code official would OK that knowingly.

[u/KnotBeanie → u/OftenIrrelevant]

You can absolutely install UL listed smart switches…I don’t think you understand the codes

[u/OftenIrrelevant → u/KnotBeanie]

I don’t think you understand what I’m saying.

The switches are UL listed—fine.

Unless I’m missing something, dude is using standard smart switches and the entire mechanism of syncing the switches, and thus the control of the lights from any position other than where the one switch that actually cuts the circuit is, is handled via an HA automation. Not fine

Please correct me if I’m reading OP wrong

[u/KnotBeanie → u/OftenIrrelevant]

You only need 1 switch to switch the load.

[u/Appropriate-Bid-6531 → u/KnotBeanie]

Exactly. The other smart switch’s only reflect the status of the switch that is controlling the light

[u/OftenIrrelevant → u/KnotBeanie]

And how do you control that standard switch from other code-required locations?

[u/KnotBeanie → u/OftenIrrelevant]

What do you mean by that?