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Replacing old bathroom switch, fan+isolator in circuit

Discussion in 'Electrics UK' started by muel2002, 27 Aug 2010.

  1. muel2002

    muel2002

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    Location:
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    I want to replace the pull cord light switch in my bathroom because it is noisy.

    When the light switch is turned on, it also turns on the extractor fan. When it is turned off the fan continues for a set time then turns off.

    The circuitry also has a fan isolator switch.

    The Old Switch has 4 connections; L1, L2, L3 and L4 plus an earth. The wiring going into the Old Switch is as follows:

    Black into L1
    Red into L2
    Wire with red sleeve into L4

    It also has a yellow wire with a light connecting L2 to L4. When the bathroom light is off the light within the switch is on.

    Their is a short brown wire only within the switch casing connected to L3 but the other end is connected to nothing. Maybe it came loose when I opened the casing. The circuitry still works with this short brown cable loose.


    The new switch has the following connections:

    Supply L
    Supply N
    Load L
    Load N

    The Earth is in the other part of the casing.



    With regard to the New Switch:

    I understand that 'L' is Live and 'N' is Neutral and I'm quite sure I understand that the Load channels the current from the mains Supply to whatever you want the electric current to Load power to i.e. Light Bulb, Extractor Fan.

    I think I understand that the current flows from Live to Neutral, so Neutral in a sense returns the flow of the current to the circuitry once the switch has done what it wants to do with the power/current and the flow of the current doesn't continue on elsewhere.


    With regards to the Old Switch:

    I'm a bit bamboozled. I would have thought that as the light within the switch turns off when the switch turns the light on, that this would mean that current is flowing between L2 and L4. From this I would make an un-confident guess that L1 is the Load, but if this is the Load and the two red wires are the Live and Neutral of the Supply I would have no idea which is Live and which is Neutral or what would be the consequences if I got them mixed up.

    What really gets me though, is that I thought that an un-insulated wire within a wire, is used as the earth, but the un-insulated wire in this case (the one with the red sleeve) seems to be part of the circuitry that is transferring current!

    Help!

    Where do I put what? Do I have the right replacement switch? Or more importantly is my wiring dodgy?

    I was hoping for a like for like transfer. But the different labelled connections within the switches, and the fact there are new and old wiring colour schemes, with the addition of different electricians with different ideas of what colours should be used for what (from what I can gather from thr internet) has brought me to a halt.

    Thanks.

    Sorry for the long post but I though it would be good to try and provide all the details (about the situation and myself) from the word go.
     
  2. crunchynut

    crunchynut

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    You say that L2 and L4 both have red insulation/sleeving. You also say that the LED is connected thru L2-L4.

    In the piccy the yellow lead seems to be connected in at one end with a red and t'other with a black....

    You are correct in being concerned about the CPC (earth wire) being mis-used. That's a big no no AFAIC, and many others would agree. Smells somewhat bodged so you would be best getting it checked (other bodges may be lurking!)

    For the sake of a few quid I would call in a spark who can have a look and sort it for you.
     
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  3. muel2002

    muel2002

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    Thanks.

    With regards to the LED, I did actually mean L1 to L4. That's what the image was for! :). I knew I was bound to make my own description bodge amongst all that writing.

    I think I will get it checked, there seems to be a theme of things not being properly done in my flat. I was sort of hoping I was being completely ignorant about the earth wire so I wouldn't have to get someone in.
     
  4. Steve

    Steve

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    If you think the new pullswitch is quiet, wait till you have it on the ceiling, it'll be much louder.
     
  5. crunchynut

    crunchynut

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    No probs Muel.

    Steve makes a good point; the pull will reverberate and sound much louder when installed. especially if all tiled walls etc and no where for the sound to be absorbed.

    I recall, possibly mistakenly, that you can get quieter pulls. Someone will know for sure.
     
  6. muel2002

    muel2002

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    I had recently begun to think that the 'quieter' pull switch I have bought would probably make just as much noise once fitted. I guess it was an ill considered impulse buy, but I then thought I might as well fit it now that I've got it.
     
  7. DIYnot Local

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