Sonoff Mini in UK - Switched Live?

Morning all,

I took delivery of a Sonoff Mini yesterday to try out; it’s unlikely I’ll find the time to play with it this side of Christmas but you never know.

I’m no electrician but something doesn’t seem quite right. I understand that to retain functionality with existing switches the mini will have to go at the ceiling rose and will be fed by the permanent live, neutral and the switch connection will have to come from the switched live.

With this in mind, all the YouTube videos seem to show the switch terminals being used or tested at low voltage. Does anyone know if it’s safe/designed to receive 230v on the switch terminals?


No it doesn’t. The sonoff mini is not designed to have 230v on the S1 and S2. If you want this, you have to use a shelly 1.

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Thanks for that; thought as much. Pretty much useless for me then! Wish the Shelly 1 was as cheap as the Mini.

That’s one thing to watch with these devices I guess… There are many comparisons between the Shelly and the Mini but none of them seem to highlight that you’re going to burn your house down if you connect the switched live in the UK!

Thanks again.

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I have done this (not for a sonoff but for a zwave dimmer).
Assuming this is UK -
At the ceiling rose, completely disconnect both of the switch wires, that way, the switch is not connected to the mains at all and works as a standalone switch. One will be brown and connected to the live passthrough on the rose, the other - blue (should have some brown sleeving on) will be connected to the live of the light flex on the rose.

See attached image - disconnect 2 and 3 and wire them to S1 and S2 (IMPORTANT - make sure the one connected to 3 is physically in the same cable C as 2, it might not be and maybe wired to 4 or 5). Connect live out from sonoff to where 2 was connected
This is assuming your rose is wired as standard


Quick tip, I replaced the front of the rose with the dome of these, leaving the old rose wiring plate in place, the bracket that comes with them slots behind the original rose plate. It gives plenty of space to put the control module in there without having to push it up into the celiing

That’s a great explanation, thanks. My house is different though; I’m told it’s a ‘loop in’ system and I have reds and blacks beneath the rose. Plus the light I’m trying to automate is switched from a 2-gang switch, so I can’t isolate the switch from the mains.

The switch terminals are designed to receive either short/open circuit, without any voltage!

(Image from here)

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The diagram above is a loop in system (A to B). the diagram has the new colours, old red is now brown, old balck is now blue.
If you mean 2-way switching (2-gang means 2 switches on one plate), ie separate 2 switches, then the end result at the rose is the same.

Old colours, 1 way switching:

Old colours, 2 way switching:

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Further great diagrams - thanks a million.

My dad is a sparky so will consult him (I don’t see him that often).

For clarity, it’s a 2 gang switch, 1 way so I’m unable to remove the supply from the switch.


Thanks for the diagrams

1x light + 1x switch easy
1x light + 2x switch sorta easy

Now, I have a three way switch setup with two lights that come on at the same time. Assume I would just do the same at the rose as with the one/two way but which light is the question?

Any suggestions?

I will of course be testing each switch and cable for voltage and continuity with diagram before wiring up

You’ll need to find the light with the switch connections. One light will be just connected to the other, probably. It might be wired with the neutral in the switch so only switched live and neutral feeds will go to the lights. In that case you’ll have to put the sonoff in the switch.

Show us your findings and I’ll try and help


Thanks Man, Will have a look again on the weekend and post back my findings

That info is not correct. see below :man_facepalming:



It is correct, that diagram does not show Live on S1 or S2. Only the labels in the original switches have L marked as that was how it was connected originally

Do you see 230v on S1.S2 in this picture ?

Horrible set of instructuions.

My bad

Found this on their other site.


Back to the original question though, If the UK ceiling rose, has the loop in / loop out supply, you can use this device.

  • Wire the feed/return to the switch directly into s1/s2 (switch is no longer ‘live’ with 240V).
  • Wire the mini off the N/L loop in (so it is powered - additional wire) Lin/Nin. You need to leave the normal LoopIn/LoopOut wired together in the rose to maintain the loop. Effectively you are spurring off the loop.
  • Wire old live to bulb (wich was linked to the switch) from Lout.
  • No need for Nout to be wired as the common is linked through the rose (this assumes a single pole relay inside the mini).

Again it will work if the loop is in the wall switch. Only issue here will be space.

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Sorry to return to and old thread but I am looking at getting either the basic r3 or mini r2 for some of my lights and found your diagrams very helpful thank you.

Most of my lights though are on 2 or even 3 gang switches, ie the first light I was thinking of trying it out on is in the loby by front door, it is controlled by a 3 gang switch, 1 switch for loby light, 1 switch for outside light and final switch is for kitchen light which is actually a 2 way switch as there is another 3 gang switch the other end of kitchen that switches kitchen light and two other lights,

So does the fact I have a 3 gang switch mean this can’t be done as you describe?


It can still be done.
The switches are separate switches, just mounted next to eachother in a plate. I’d label them to ensure they dont get connected to mains in future.

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Great thanks, I wasn’t sure if they where each treated as individual switches or some way where they are all powerred as one some how.