Change LNLN light switch

[London8046]

Hello,
I want to change my light switch to a new one and discovered that the old switch has an L - N - L - N wiring, which I have not come across before (see photo).

This is for a bathroom light that has only one switch, so not sure why this wiring was used. Can I use a simple two-way switch (Com, L1, L2) to replace the old one and how would I do the wiring? Thanks!

 

[flameport]

You need a double pole switch, which is what you have now.
Other switches cannot be used as they do not work in the same way.
Presumably an extractor fan is involved here.

 

[Taylortwocities]

Also: that metal switch plate must be connected to earth. It isn’t at the moment.

 

[plugwash]

It's a double pole switch, and will more likely than not need to be replaced with another double pole switch.

Looking at the wiring I strongly suspect that this is part of a set-up where multiple lights are associated with the same fan. Double pole switches are used to keep the fan and light wiring seperate and hence allow both switches to turn on the fan while each switch only operates one light.

 

[London8046]

Yes, looks like it is a double pole switch. But not sure why it was used in the first place. There are only 2 led recessed lights, no fan or other appliances attached to it. Could there be a way not to use a double pole switch as a replacement?

 

[Taylortwocities]

. Could there be a way not to use a double pole switch as a replacement?

not until there is a better understanding of what is going on.
Questions

To the left lower L terminal there is a blue wire connected. What is that for? Is it a neutral or is it a switched live - if so the blue wire should have a brown marker.

Can’t see what, if anything, is connected to the top left (L) terminal. Is that one of the brown wires?

The right hand terminals should be neutrals (is the N terminals ) but there are brown wires in there. Are those brown wires permanent lives?

I have a vague idea of what is going on but would need to see what other connections/wires are in the back box.

 

[London8046]

Here is another picture of the wires going into the switch.

Hopefully this helps. Thanks!

 

[Taylortwocities]

It looks like the brown and the blue that are in the L terminals are the two switch wires.

What the three wires are in the N terminals IHNI. Not scientific but I suggest you try this. Power off!!
Remove the three wires in the N terminals. And put them together in a separate connector.

Power back on.
Does everything still work? Does the switch work the light.

If so, you can replace the switch with a standard switch.

If something doesn’t work then you going to need a voltage tester.

 

[London8046]

Ok, so I moved over the brown and blue wires from the L terminals into a standard switch and put together the 3 brown wires from the N terminal into one. Result: light turns on but I can’t switch it off. What does that mean? Below picture of the wiring.

 

[London8046]

Update: i separated the 3 brown wires that were in the original N terminal and put them into the standard switch and capped off the brown and blue wire from the L terminal. All seems to work fine now, lights turn on and off.

Does not make sense to me why it would work but somehow it does. Any insights? Is this a safe solution?

 

[Taylortwocities]

Update: i separated the 3 brown wires that were in the original N terminal and put them into the standard switch and capped off the brown and blue wire from the L terminal. All seems to work fine now, lights turn on and off. View attachment 309044
Does not make sense to me why it would work but somehow it does. Any insights? Is this a safe solution?

No insights- without you doing a lot of testing with a multimeter, or me bring on site!
But if it works then I guess that’s part of the mission.
Is it safe? Not until you connect that metal switch plate to earth!

 

[Adam_151]

Is there now a fan thats not triggering when you go into the room, or perhaps a MVHR unit that no longer goes from trickle to full?