Ste0d0

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Jan 10, 2022
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Hi all,

I'm hoping someone on here can shed some light on an issue I currently have with a bedroom light switch.

Yesterday evening, I attempted to change the standard light switch in one of the spare bedrooms for a dimmer switch. I initially swapped each wire, like for like, so that the COM's wire from the old switch was put into the COMs terminal of the new dimmer switch and so forth.

With the electricity turned back on, everything seemed fine, as the dimmer switch was working as intended, however, I soon discovered that the lights in my bedroom, en-suite and walk in wardrobe were acting up, as they'd either fail to turn on or began to flicker when they did work etc. Unsure what might be causing this issue, I decided to cut my losses and just refit the old switch, believing everything would go back to as it was before I had decided to meddle with it.

It was at this point that I realised that the L2 terminal had been removed (see photo) from the original switch, which would probably make sense, as it is just a 1 way switch, but what I'm now wondering is what the third wire is for? Where should it go? It was originally just pushed into where the L2 terminal would be. Despite this, I refitted the switch as it was originally and the light is working fine, but now none of the lights in my bedroom are working. If I swap the wire in L1 terminal for the one that's sitting in the empty L2 terminal, the switch no longer works in the spare room, but turns on the lights in my bedroom. I'm totally at a loss as to why the switch will no longer work as it had originally.

If anyone has any idea how I can rectify the issue and if possible, install the new dimmer switch, I would be eternally grateful :) Failing that, I'll settle for leaving the old switch on the wall.

Cheers

Steve
 

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looking at the pictures ,me thinks you should seek an off attention
of a local spark ,considering either on of those legs need to be put back in the correct terminal.
 
Last edited:
A third brown wire suggests a looped feed to another switch. Using the original switch, connect 2 browns to COM and one to L1
Nothing should have been in L2

Any of the following may happen.

1. You got it all right! Congrats.
2. The bedroom light is always on. The spare room doesn’t work until you turn on the bedroom.
3. Neither the bedroom or the spare room work until you turn on the switch


With only 3 browns, there’s a limit to how it can go. Mark them with sharpie pen 1 line, 2 line and 3 lines. Connect them 1 and 2 in COM, 3 in L1.
Off that doesn’t work, swap 2 and 3
 
I think the Lighting feed to the common, spare room and bedroom to L1.
You can still use the dimmer, although, I might be tempted to use a 2 ganged switch/dimmer and control the two rooms separately.
 
. It would have been in the Com terminal, along with another cable.
It will be two wires in one terminal and one in the other. Ideally, the two will be in the com. terminal, but it will work just as well if the two are in the L1 terminal. Just has to be the right two.
 
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The possibility he might put the wrong
Tails in, heaven forbetsy.
 
A third brown wire suggests a looped feed to another switch. Using the original switch, connect 2 browns to COM and one to L1
Nothing should have been in L2

Any of the following may happen.

1. You got it all right! Congrats.
2. The bedroom light is always on. The spare room doesn’t work until you turn on the bedroom.
3. Neither the bedroom or the spare room work until you turn on the switch


With only 3 browns, there’s a limit to how it can go. Mark them with sharpie pen 1 line, 2 line and 3 lines. Connect them 1 and 2 in COM, 3 in L1.
Off that doesn’t work, swap 2 and 3
Connected two of the wires to the COM terminal and the third to the L1, as suggested and it worked first time round.

Cheers, littlespark.
 
Connected two of the wires to the COM terminal and the third to the L1, as suggested and it worked first time round.

Cheers, littlespark.
You'll then have to turn the switch plate upside down !
 
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No you won't !
You will if there are any markings such as 'this way up', 'leave switch on', 'outside light', for direction or even some company advertizing
 
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Mate, with a one way switch as long as you have the top at the top it makes no difference at all whether the feed is in C or L1 or vice versa.
 
Mate, with a one way switch as long as you have the top at the top it makes no difference at all whether the feed is in C or L1 or vice versa.
n
bo
but if 1 is in L2, it's Australian.
 
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And with old MK 2 way switches it was always C & L2 when using as a 1 way, but that's nothing to do with it. 😁
 
Mate, with a one way switch as long as you have the top at the top it makes no difference at all whether the feed is in C or L1
Of course it doesn't matter, but you will have to orientate the switch plate according to the terminations assigned to C and L1 and as long as the switch plate has nothing engraved on its face.
 
it's only if 1 wire is in L2 that you have to turn it upside down. if using C and L1. either way round nothing really matters.


 
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Precisely, and great song too. 😀
 
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Location
ireland
If you're a qualified, trainee, or retired electrician - Which country is it that your work will be / is / was aimed at?
Ireland
What type of forum member are you?
DIY or Homeowner (Perhaps seeking pro advice, or an electrician)

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One Way Switch Issue. Help!
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