I live in Spain.

I have this switch near my door: enter image description here enter image description here

Black is live and the 2 greys go to the switch/outlet in my bedside: enter image description here enter image description here

The squares are switch to the left and outlet to the right.

  • Green/Yellow is Ground.
  • The Blue on the top right I assume is Neutral (Does not come from the door's switch)

I'm trying to add this smart switch: enter image description here

However I don't think the 2-way switch wiring they show matches mine.

From the vendor: enter image description here enter image description here

Is there a way to add this smart switch while still being able to use the physical switches? If needed I could remove the switch/outlet on the bedside.

  • 4
    Obligatory note for North Americans that two way switch everywhere else in the world is what we call a 3-way switch, for reasons not terribly obvious. Likewise 3-way is what we call 4-way.
    – Ecnerwal
    Dec 21, 2023 at 13:41

1 Answer 1


I'm not truly familiar with EU wiring, I'm used to UK, but that looks very odd to me. It looks like your switched live [blue] comes to one switch, but leaves from the other [black]. Between the two all you have are two alternate travellers [grey]. That will work as a simple 2-way, of course, but it means neither switch has a permanent live & neutral to feed your smart switch [which must have power at all times, you can't switch it off.]

So, what you have visible is the section outlined in green, but your live feed [in red] must be up in the ceiling - this is consistent with how much of the UK is wired, except for the split drop.
To wire this as standard requires 3 wires between the switches [plus earth], with the switch drop to only one of them. Even wired this way your permanent live/neutral is in the ceiling, not in the wall.

The smart switch assumes you have a US wiring standard, power in the wall not the ceiling - which is now used in UK/EU new builds, precisely to support smart switches, but not older homes.
To get this to work you're going to have to find the mains origin & drop it down the wall to one switch, and also drop one of your 'stray' switched lives so it can reach the smart switch, not be over the other side of the room as it is now. This is not a simple task unless you want cables running on the surface in conduit:\

enter image description here

I found a mention of this wiring method on LightWiring, unfortunately now defunct, but fortunately has been preserved on WayBack Machine.

enter image description here

  • TBF, many homes in the US were built with "switch loop" wiring prior to ~2008, too. It saved wiring expense. It's now outlawed for precisely this reason. (It never made any sense to me why someone would do it that way, but I'm no professional electrician, so what do I know...)
    – FreeMan
    Dec 21, 2023 at 17:52
  • @FreeMan - I just grew up on this system, never questioned it tbh. There was no need for power in the wall until smart switches were invented ;) Wiring a whole floor before the floorboards go down on a bunch or stars/spurs this way is simple.
    – Tetsujin
    Dec 21, 2023 at 17:58
  • The place is 31 years old, so you're probably right. This is what I had drawn after checking the cables imgur.com/NdNnmLa I have the outlet's top and bottom left switched in the drawing though, I'll probably cut the live on the door and put a gray in it's place so it acts as a regular switch, then add a new live in the bedside switch with the neutral that's already there, remove the physical switch and outlet and put the smart switch in the hole and a plastic cover. Thank you.
    – Daviid
    Dec 22, 2023 at 7:59

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