Light Switching Problem

Discussion in 'Electrics UK' started by dandyandy, 2 Oct 2007.

  1. dandyandy

    dandyandy

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    Hi there,

    There are 4 lights which are relevant to this problem, and one of them (LIGHT A) was on a 2 way circuit. I have changed a 2 gang switch (labelled SWITCH B) to a dimmer switch which is 1 gang only (labelled SWITCH C) and made the changes on the diagram.

    I reckon SWITCH A was wired inappropriately as it would switch both LIGHT A and LIGHT B, and was 2 way with one of the switches on SWITCH B, which would control LIGHT A. The thing is, LIGHT A is an outside front porch light, so to my mind it doesn't make sense to have that being switched from just outside the door, and from the main inner hallway? Could it be the person who made changes to the switch, put the wrong blue and yellow wires to the wrong "switch" in the 2 gang "switch unit", meaning the wrong light was being controlled by the secondary of the two way switches (God I hope this makes sense!)?

    Anyway, the big problem I'm having now, is that LIGHT D will not come on, if LIGHT A is switched on! LIGHT D is in another room altogether, and on a 1 way circuit?

    Any help appreciated if you can help me see whats gone wrong!

    Thanks in advance

    DIAGRAM:
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  3. fireman22

    fireman22

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    firstly link in top right hand switch the link must have been between lower C terminal and either L1 or L2 of top part of switch ( the L terminal which has the permenant live) i am going to carry on looking at it but wanted to be the first to post a reply
     
  4. fireman22

    fireman22

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    in switch A are you sure the red of the 3 core cable is in the C terminal as per your drawing? and not one of the other reds
     
  5. fireman22

    fireman22

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    hang on you say you have changed two gang to a one gang dimmer but what about the three core cable then the red yell & blue?
     
  6. fireman22

    fireman22

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    have you only changed / opened and moved wires in the switches or have you also changed a light fitting
     
  7. dandyandy

    dandyandy

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    Sorry forgot to put that in the diagram, they've been made redundant by placing them into individual terminate blocks. The blue, the yellow and the red(com) of that set.
     
  8. dandyandy

    dandyandy

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    The red of the 3 core is actually going into the lower COM.(odd, right?)

    No light fittings have been changed, only the switch.
     
  9. fireman22

    fireman22

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    i am assuming from your drawing you have twin red cables and three core cable (red yell & blue)
     
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  11. fireman22

    fireman22

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    if you have done away with the three core you must dump it both ends and put the reds of the top switch one in C one in L1 the link then goes between C and C. you should / must put the perm live in C in the top switch try it one way then swap it if it isnt working unless you have a tester of course
     
  12. dandyandy

    dandyandy

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    What is actually in there is one 3 core, and three 2 core (red and black), but all the blacks are on a single terminator block.
     
  13. fireman22

    fireman22

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    that is put individual connector blocks on both ends of the three core and dont connect it to any part of the switch
     
  14. fireman22

    fireman22

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    was it always like that tho all blacks in a terminal block?
    sounds as if you have a pair of mains on one pair and two switched live/neutrals out.
    have you any way of finding which red is the perm live, neon screwdriver even this then goes into one of the C terminals with a link to the other C terminal with the two other reds going into the two L1 terminals then this switch should be ok
     
  15. dandyandy

    dandyandy

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    Yep, always had the blacks in the terminal block. I think all the switches in the house are like that.

    Thanks for all your help!
     
  16. dandyandy

    dandyandy

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    Ok, thanks. I'll try that, however, what do I do with the red that is already in COM on the top part of the switch?
     
  17. fireman22

    fireman22

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    do what i said in previous post first, then come back to me
     
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