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bigmac
Junior Member
Joined: 05 Aug 2008
Posts: 3
Location: Shepherd's Bush
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 Posted: Tue Aug 05, 2008 11:31 pm Post subject: wire loose in two-gang switch - where do I put it? |
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Dear experts!
We have a two-gang wall switch for kitchen/dining area lights.
Each gang is in fact a dimmer (which I don’t think is relevant!); either is switched from a second point as well.
One of the two switches failed and on inspecting it, I noticed the yellow “strapping” wire (I think it is called) had come adrift from the terminal.
I would re-connect it, if I knew which terminal it goes on! I ruled out trial and error on this one…
The sequences of wires are as follows:
Left hand switch – which works – has
L1 – Black + Blue
C – nil
L2 – red + red
Right hand switch – the failed one:
L1 – black
C – nil
L2 - red
The cables to the switch come out of the wall in a clump but I am pretty sure the two wires to the right hand switch are from one cable; I can’t however tell which of the other cables produced the detached yellow
I am assuming the RH switch failed because it has a wire to the light and a wire back and nothing connecting it to the circuit – this is what the yellow should be doing… however I don’t know if it is to go back into L1, C or L2.
I did check the obvious – did any of these terminals have a nub of severed wire in them which would indicate where the Yellow had been fixed – and no, nothing there…
I THINK the answer is – “fix it to L1 or L – it doesn’t matter which; fixing to C is pointless as it bridges the switch and leaves the light on constantly ….”
But as I said the point of this post is to ask for advice from someone who knows for sure!
Many thanks |
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Rich-Ando
Approved Electrician
Joined: 24 Mar 2007
Posts: 2623
Location: Derby, Derbyshire
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| Posted: Tue Aug 05, 2008 11:36 pm Post subject: |
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it should be in C.
if you only have wires in L1 & L2 the light will never work. |
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bigmac
Junior Member
Joined: 05 Aug 2008
Posts: 3
Location: Shepherd's Bush
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| Posted: Sat Aug 09, 2008 5:22 pm Post subject: |
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Doh;
Really appreciate your help Rich-Ando, but ...
Having taken the thing apart completely I am now able to read the terminals ... which unhelpfully were facing INTO the wall ... I discover the sequence is in fact:
Left hand switch – which works – has
L1 – Black + Blue
L2 – nil
C – red + red
Right hand switch – the failed one:
L1 – black
L2 – nil
C - red
does this mean the yellow strapping wire goes to L2 on the right hand switch?
THANKS |
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Rich-Ando
Approved Electrician
Joined: 24 Mar 2007
Posts: 2623
Location: Derby, Derbyshire
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| Posted: Sat Aug 09, 2008 5:34 pm Post subject: |
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that doesn't add up either.
the only way that you would get a live in the common of a switch on a 2-way circuit is if the circuit was wired in singles. having a 3-core cable in there makes this sound completely wrong 
did you take the switch off at some point?
on a 2-way switch you normally have 2 cables in L1 & 2 in L2 with just one in C. there are other combinations for this but they are NOT the normal way of wiring it.
i do agree that logically it sounds like the wire has come adrift from the last terminal. you can't do any damage trying it so turn the power off and go for it. |
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bigmac
Junior Member
Joined: 05 Aug 2008
Posts: 3
Location: Shepherd's Bush
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| Posted: Sat Aug 09, 2008 6:42 pm Post subject: |
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last terminal meaning the C? or meaning the L2 which has nothing in it?
Happy to try anything that doesn't risk blowing the circuit!
these aren't two-way switches though, they are 2 x one-ways
there are definitely three cables plus an earth coming into the back of the wall box - tight and barely enough to work with!
one cable has the red and black going into the non-working switch
the other two feed the working switch: a red and blue or black in one of the cables, red, blue/black and the "loose" yellow from the other. I have been assuming it is this detached yellow which is meant to carry the current over to the non-working switch?
does this help?
background is: I replaced the dining area wall lights about 2 years ago; no problem; sometime around then also one of the two dimmers failed and i replaced the switch; it has been working happily ever since up till 2 weeks ago; when i replaced the switch I did all the sensible things like write down the sequence of wires before taking it apart.
The only mistake was chucking away the piece of paper afterwards! I wasn't expecting a wire to work loose!
thanks |
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Rich-Ando
Approved Electrician
Joined: 24 Mar 2007
Posts: 2623
Location: Derby, Derbyshire
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| Posted: Sun Aug 10, 2008 9:51 am Post subject: |
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hmm, that confuses me even more now, no wonder you are confused 
the presence of a 3-core cable that you say IS NOT used for 2-way switching makes it sound like somebody was very lazy when they put the wiring in.
if they are not 2-way switching circuits then putting that yellow into L2 will make no difference at all, it needs to be in one of the other terminals although they already sound like they are too crammed.
is there any chance you can take a picture of the switch with the wires?
normally we can get the answer straight away but this doesn't sound normal, unless i am just overlooking the obvious because i cannot see it. |
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Stoday
Electricity economics consultant
Joined: 20 Jan 2006
Posts: 3234
Location: Sitting on the Bog
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| Posted: Sun Aug 10, 2008 12:47 pm Post subject: |
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Thank goodness you can't understand it RA.
I thought I was going senile because I couldn't understand. I'm pleased I haven't got early onset Alzheimer's after all
_________________
УГМ МОД — Пошёл на хуй |
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Rich-Ando
Approved Electrician
Joined: 24 Mar 2007
Posts: 2623
Location: Derby, Derbyshire
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| Posted: Sun Aug 10, 2008 2:07 pm Post subject: |
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| Stoday wrote: |
Thank goodness you can't understand it RA.
I thought I was going senile because I couldn't understand. I'm pleased I haven't got early onset Alzheimer's after all
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i'm not happy with you anyway...in the other thread you mentioned "don't any of you young lads know how to wire 2-way with just a twin between the two?"
don't that just make me feel in your age bracket...i used to wire them that way as 3-core didn't exist   |
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