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Sonoff with 2-way Physical switches

Hello, I have a scenario in which I have 2 physical switches to control a light and I want to connect it with my sonoff 4ch pro r2. I was thinking of connecting one of these physical switches to sonoff so that I can control the light using the physical switches and eWelink. Can anyone provide me a connection diagram for this scenario? I understand that the live status of the switch won't be updated properly if we combine it with physical switches. I'm okay with with that.

Best Answer


"I wonder if is possible..."

No it is not possible.  The Sonoff T1 is a simple 1-way switch.  It will not replace a 2-way switch and allow the other 2-way switch to function properly.

No it is not possible.


The Sonoff T1 is not a 2-way switch design, so you are not able to use it to replace one switch (gang) in a room which has the lights operated by 2 separate switches. I assume you know that the T1 also requires a neutral wire, which may not be present in your existing switch box?

You could use one channel of the 4ch Pro to replace a single gang (2 channels for 2 gangs), but that is quite large and would need careful positioning.



The Sonoff T1 is not a 2-way design, so it cannot replace a switch (gang) in a room where the lights are controlled by 2 separate switches.

I assume you know that it also requires a neutral wire, which may not be present in your existing switch box?


One channel of the 4ch Pro can be used to replace a 2-way switch (2 channels for 2 gangs), but that is quite large which presents its own problems.

Thanks for the reply. Neutral cable are there. In fact the switch is working as I'm able to use the switch to turn on and off both lights. What is not is the two ways, using the normal switch. I could buy and extra 2 gang sanoff switch and create an scene as some people have described but I will ended with the same problem because the normal switch also controls another light using 2 way. As I can see I'll need to buy 4 2 gang switches if I want to have a similar setup as I used to have with the initial 2 normal switches.

If you can solder a couple of wires in parallel with one of the  buttons, then you can use one channel and replace your wall switches on the 2 ends of the circuit by momentary switches in both places, both connected in parellel with the original Sonoff button. 

This way you can turn on and off indistincly from either place, from the app or even google home / alexa. It will keep everything syncronized.

Good luck !

Why Sonoff doesn't build a wall switch with NO & NC contacts and a simple current sensor to detect the on state of the load is beyond me.  Users could replace both regular and 2-way switches with it.  They already have the parts and the engineering done and would sell them by the boatload.


It would be nice, but I don't think it can be done with a Triac, design which is used in their smart switches. To operate properly it would need a relay, which then has issues of space and the "latched on" state of the coil. If there was a power cut, off/on, the lights may then be incorrectly powered on ...or some extra logic control required. 

I'm guessing that's why smart switch manufacturers are avoiding that type of device.

They could easily use a relay instead of a triac.  The smart light switches I am using are Oittm  and they  use a relay.  The relays in the basic and pow are rated at 100% duty cycle so always on isn't an issue and Sonoff incorporates a "Keep" setting which will bring their devices back up in the same state they were in when power was lost.  And hey, if they wanted to go real fancy a mechanically latched relay/switch could be used.  Basically all you need is the circuitry of a Sonoff  POW with NO and NC contacts built into a light switch.  They already have most of the product developed it just needs to be built into a light switch package.

As a retired engineer I just don't see this as a tough problem to solve and there IS a market for it.  Leviton has some devices out but they are expensive and in my opinion not as good a solution as what I am talking about.  I am surprised one of the Chinese manufacturers has not put one on the market yet.

EW, do you have a link for the Oittm switch you are using, the ones I have seen are single pole only.


Like all the rest it is SPST.  I mentioned it only to illustrate that a relay can be used in a light switch instead of a triac.

 I've been interested in this question for some time and, like the OP,  realised that the live status of the switch would not be updated properly in the ewelink app when one of the manual switches was used to change the state.

But I've recently discovered the Sonoff Mini, and having received one today and incorporated it into an existing mutli-way switch setup (2 x 2 way and 1x crossover/intermediate), it works perfectly.  The Mini apparently detects any change of state caused by the manual switches and responds appropriately to the next change of state by either the Mini or any of the manual switches. 

I had thought that changing the state by using the app would mean that the next time I changed the state using one of the 3 manual switches would mean that the manual circuit might need to be switched twice for the Sonoff to "catch up", but that is not the case at all. 

The Mini only controls one light/device, but buying 4 of them is only a little more costly that buying one 4ch pro r2.   

It seems to me that the Sonoff Mini is a much better option if you want to include manual switches in your circuits.

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I'm new to home automation, and have purchased T1 3 gangs switches (11 units so far, more to come), replacing all existing switches. Like the OP, I was wondering how to replace the 2-way switches for the stairs. I encountered this post. After reading and doing some thinking, I came out with an idea. Replace 1 of the switches with a normal standard T1 switch (I'll use 3 gangs, 1 for stairs, 2 for other lights). It will now behave like an ordinary 1-way switch. The other switch, forget about (remove) it. Replace it with an RF transmitter switch, instead. No wiring required. So the operation will be.. T1 switch does the actual switching work, the RF switch toggle the T1 switch.
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