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I found some similar questions but none actually sort out my problem.

I bought a new IKEA light fitting and its electrical box has 4 holes (2 for N and 2 for L). The instruction said to put 1 N to N and 1 L to L. And I saw many videos online doing the same thing.

Mine is different. I have two cables (each has 3 N/L/E). I know that one of them is for the switch while the other is for the consumer unit. I tried different combination:

  1. Putting only the consumer cable in --> the light is always on. The switch does not work
  2. Putting only the switch cable --> the light is not on.
  3. Putting both of them in, 2 N from the two cables go to 2 N holes. Likewise, 2 L from the two cables go to 2 L holes. --> The light is on even when the light switch is not on. When I turn the light switch on, the light goes off and the main switch (of the room) switches off as well (meaning the combination is causing some conflict).

I tried different combinations of the third (changing the order of the two N and the two L) but none working. Can someone please help?

The cables from the ceiling The socket from Ikea

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    It's always good to include pictures of the wiring in the box at the light fixture, and, if possible, at the switch. – FreeMan Oct 7 '20 at 10:54
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    Can you post a photo of the inside of the switch box please? – ThreePhaseEel Oct 7 '20 at 11:47
  • Yes, I have included some pictures @FreeMan – Duy Bui Oct 9 '20 at 13:14
  • This is obviously not US based, and that's my only frame of reference, so this looks very odd to me. I'd double check that you are code-compliant to have the cables coming out of the ceiling(?) like that without being enclosed in a box (I'm certainly not saying it isn't but it looks odd to my US expectant eye), and what the heck is that black bar that they seem to go through? Below that bar, it seems the the pic has been edited to remove the background, is that the case? – FreeMan Oct 9 '20 at 13:44
  • The black bar is from the new light fitting. This is the UK model but I guess it should follow the rule of 3 wires per cable (L/N/E). No, the picture was not edited. The background was automatically blurred since the picture was taken by Samsung S9 – Duy Bui Oct 9 '20 at 17:17
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This is a switch leg or that’s what we call it on this side of the pond. How we would wire it here is to connect the hot or L of the consumer unit to one of the wires going to the switch then the line coming back from the switch is the switched hot L. The switched hot goes to the L the N from the consumer unit in the n and connect earths

I did not put colors in since you did not mention them and I believe there are 2 or 3 possible combinations based on when built.

The wire going to the switch with the consumer unit hot we would use our normal color wire for N or white so that line is always hot and the switched hot brown or whatever is hot when the switch is on but the neutral always being hot can’t be mixed up as a neutral then we put tape or mark it as a hot.

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  • Hi @Ed Beal, thanks for your answer. I am still not sure how to connect using your suggestions. I posted some pictures, hopefully, it can help. – Duy Bui Oct 9 '20 at 13:15
  • You will need to identify the line from the consumer unit. That hot or brown wire would be connected to the blue wire. When the switch is on the remaining brown would go to the brown for the light and the blue would go to the blue on the light. On this side of the pond we would use a wire nut to connect the consumer unit line or hot to the switch blue. A 2 hole wago connector would work I think they are used on your side. – Ed Beal Oct 9 '20 at 18:53
  • Hi @Ed Beal, I am still not sure how to do it. Let make it simple, we have Switch L/N (Brown/Blue) Consumer L/N (Brown/Blue) Ikea box: 4 slots - 2 L and 2 N Are you saying we put 1) Consumer L (Brown) and Switch N (Blue) to the 2 L slots in the Ikea box. 2) Switch L (Brown) to one of the N slot in the Ikea box – Duy Bui Oct 10 '20 at 18:00
  • If you cannot identify the hot cable I cannot help and no one else can if you have the wrong cable connections as I outlined it will be switching the neutral a potentially hazardous condition when changing lamps and or if the shell is grounded to the fixture it will probably trip your RCD in the main panel but the shell and ground are not normally connected. When the brown wire from the consumer unit cable or hot is connected to the blue to the switch cable then you only have a blue and brown left those go to the light if you cannot follow these instructions please find an electrician to do it – Ed Beal Oct 10 '20 at 18:11
  • Hi @Ed Beal, if the hot cable is the L of the consumer unit then I can identify them. From the picture (6 wires from the ceiling N/L/E from the two cables - Switch and Consumer), I can identify which one is Switch and which one is Consumer. – Duy Bui Oct 11 '20 at 8:29
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The 2 L's on the one side is the hot in and out to feed through to another switch. The switch leg comes from the other. Neutral doesn't switch its tapped together. You can find the hot by touching the wire from the light to the others one at a time and when it comes on thats the hot.

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    There are safer ways to find the hot wire than touching the wires together. – JACK Oct 17 '20 at 15:28
  • Hi there, I know which cable is hot (i.e. consumer). Are you suggesting putting two L cables (i.e. two brown) onto the IKEA box (onto two L holes of the IKEA box)? The two N cables (i.e. two blue) are not going anywhere. They are tapped together but won't go to any hole in the IKEA box. @Jo2ker – Duy Bui Oct 20 '20 at 15:01

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