Hi,
I’m quite new to HA but have decent understanding of electronics. However, even after reading several posts here I am really confused about smart relais (Zigbee in my case). I bought four cheap relais from China and my goal is to replace dumb 2-way switches with relais and to have everything still working when the coordinator is down.
The switches I have seem to only detect continuity between the two switch inputs. Here is a screenshot from the “manual”:
It states explicitly “To ensure safety, do not connect neutral wire or live wire to it”.
However, I find many instructions online where neutral is connected to a switch input or even the live wire. Does this simply depend on how the switch is built? Is there any way I can use the 2-way functionality with my switches without having a third traveler wire between them?
Yes, switching could be done even at logic level, we don’t know that. Obviously you could verify with multimeter if s1 or s2 has continuity with N or L.
Anyway, you can probably make it work with existing wiring replacing the 2-way switches with momentary switches. Jus make sure your relay has “Momentary Working Mode”.
Thank you. Temporary switches sound good but aren’t an option (spouse approval).
I don’t know why I did not think of measuring it, . Strangely, the two almost identical relais had different results. One (eWeLink) has LIN and S1 connected and live voltage on S1 and S2 when powered.
The other (Tuya) has no connection from switch inputs to anything and has half the input voltage on S1 and S2 when powered.
So I guess as long as the relais and the first switch are on the same fuse, this should work for the first type of relais:
I don’t know how to read that…
Like I wrote before the circuit can be N to sw, L to sw or neither.
I don’t know what you mean with temporary switches. What I proposed is momentary switch, just like normal switch but with spring inside. If that’s not passing wife approval, I don’t envy you…
That’s the weird part. I do not measure continuity from S1 to any other terminal, same with S2. When the relais is powered with 230V (I forgot to mention that I am in Germany) I measure 122V between S1 and Nin and between S2 and Nin so the S inputs aren’t connected directly to any other terminal.
Sorry, I meant momentary switches. Yeah, feedback hasn’t been too positive so far, best to leave the old switches in for now . Also, it’s a rented apartment.
Ok, thank you. Do you think that the wiring suggested in 2-way relais, how even? - #3 by Onprem should work if the product description states that switching is detected between S1 and S2 and S2 has continuity with LIN? I could not yet try it because none of my wall boxes have enough space to accomodate a relais.
That’s correct. Most smart switches don’t even have S2, because in that case it’s just wasting space. For example Shelly has wiring scheme simple like this:
But when you are dealing with non certified AE devices, you need to verify it with multimeter. More than once I have seen devices that have one circuit printed on the device and different on the box/manual.
Thanks again, that makes much more sense now. I would love if there was a tag for that (e.g. “live wire switching”) that manufacturers would list in the product description. For a beginner it is difficult to find that out before (or even after) buying a relais.
The problem is much bigger. When you buy a “tuya” device you often can’t even find the manufacturers name anywhere on the device or package. No ID, no certifications, nothing…
. Strangely, the two almost identical relais had different results. One (eWeLink) has LIN and S1 connected and live voltage on S1 and S2 when powered.
. Also, it’s a rented apartment.