Im trying to replace a switch and im not sure how the wiring should be done properly. I was expecting a simple wiring (live,nutral and earth) to be there. But once i removed the socket it looks like a three phase line(guessing by the colors).

The new switch im using the switch

Old wiring old wiring

Back of old switch and new switch(new one on the right) enter image description here

Any idea about how the wiring should be done properly? Thanks

  • a multimeter would tell you instantly how many hot (phase) you have.
    – Ruskes
    Jul 12 at 23:56
  • I do not see 3 phases, I see only one
    – Ruskes
    Jul 13 at 1:17
  • Can you post a photo looking into the back of the backbox please? Jul 13 at 2:21

1 Answer 1


I am not real familiar with European wiring but I think this is the only way the old switch could work.

This is plain-old single phase power.

The brown wires are hot, one in from the power source and one on to the next switch or outlet. The blue wire is connecting the brown wires together (the paired holes are internally connected). The black and white wires are switched hots going to the lights (or switched outlets).

The thing that was confusing is that switch 2 is connected backwards: hot is going to the switched output side of the switch and switched hot is going to the line side. The switch really doesn't care which way the power goes, as long as you aren't using it was a (US called) 3-way switch.

For the new switch, connect the two brown wires to the "L" terminals and connect each of the black and white wires to one of the arrow terminals.

  • @FreeManActually, the brown wires are both hot. The lights are connected to the black and white wires.
    – DoxyLover
    Jul 13 at 17:43
  • D'oh! Totally misread that... You are absolutely correct.
    – FreeMan
    Jul 14 at 14:33

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