Help!! Wiring a new light fitting

Discussion in 'Electricians' Talk' started by Dean@DIY, Nov 26, 2012.

  1. Dean@DIY

    Dean@DIY New Member

    Hi All,

    I am completely lost and really need help getting a new light fitting wired. I took down the original light only to find there are THREE seperate cables all terminated at one block which has multiple connection terminals. My new light fitting has 1 x Live terminal, 1 x Neutral terminal and 1 x earth terminal but I have... 3 x live wires (red) 3 x neutral wires (black) and 3 x earth (yellow and green)

    I wired them all into there repective ports (3 live into 1 live port, 3 neutral into 1 neutral port etc) and it blew the fuse as soon as I turned it on! My question is, is it ok to have 3 of the same wire going into one terminal respectively? and should this generally work ok? and subsequently is the issue elsewhere??

    Thank you in advance
  2. G Brown

    G Brown New Member

    No! Google wiring lighting! The switch will use the live and neutral as the break circuit so in effect both a black and  a red wire are live....
  3. Dean@DIY

    Dean@DIY New Member

    Thank You for your response, I have googled it but cant understand and of the diagrams, I am a complete novice!! How do I find out which wire is which? Do I need all the lives together and one of the blacks in with the live then?
  4. G Brown

    G Brown New Member

    You need a circuit tester. Call an electrician. It won't take them five minutes and you won't have any fires or blown fuses! :)
  5. Dean@DIY

    Dean@DIY New Member

    Seems like I may have to!! Thank You
  6. wally

    wally Screwfix Select

    It would have been so much easier if you had noted your connections before you disconnected the old one, your not alone though.      Generally all 3 reds connect together inside the fitting but not connected to the fitting.  Your problem lies with the 3 blacks, 1 is actually used as a live (switch wire) & you obviously did not note which one it was (on a modern install this one would have had a red or brown sleave on it).  As you have now likely put a a live & a neutral through the switch it has probally blown the switch to bits or welded the contacts together.
  7. spinlondon

    spinlondon Member

    One pair of red and black wires are from either the fuse box, or the light on the circuit in front of the light you are working on.
    Another pair of red and black wires go to the next light in the circuit.
    The final pair go to the switch that controls the light you are working on.
    The three red wires should be connected together.
    Two of the black wires, to the other lights on the circuit should be connected together, along with the neutral from the light fitting you are installing.
    The third black wire which goes to the switch that controls the light you are working on, should be connected to the live terminal on the fitting you are installing.
    The black (switch wire) should have been marked with some red tape to indicate that it is not a neutral wire, but is in fact live.

    Is it in fact a fuse that has blown, or an MCB that has tripped?

    What you need to do, is switch off the light switch that controls the light you are working on.
    Connect all three reds together, and just two of the blacks (call them No.1 and No.2).
    Don't connect anything to the new fitting yet.
    Replace the fuse, or switch on the MCB and see if all the other lights are working (make certain that you don't touch the spare black wire (No.3), and that it isn't touching anything else).
    If all the other lights are working, then the spare black wire (No.3) is the switch wire that should be marked red.
    If any or all of the other lights are not working, then you need to swop one of the black wires (say No.2) with the spare one (No.3).
    Again if still any or all of the lights are not working, you will need to try another combination (swop No.1 with No.2).
    You should start with No.1 and No.2 connected, then No.1 and No.3, then end with No.2 and No.3 connected.
    One of these combinations will be correct and you will know this, because all of the other lights will work.
    Obviously between checking, remove the fuse, or switch off the MCB.
    Once you have determined which of the black wires is the 'switch wire', you can connect it to the live terminal on the new fitting, connect a wire between the neutral on the fitting to the two black wires in the rose, connect an earth wire (if required) and fix the fitting to the ceiling.
    switch on and every thing should be hunky dory.
    tonycluedo likes this.
  8. Mr. Handyandy

    Mr. Handyandy Screwfix Select

    You should have reminded him NOT to use the switch at any time during those tests!

    Mr. HandyAndy - Really
    tonycluedo likes this.
  9. spinlondon

    spinlondon Member

    No need, you just did it.
    tonycluedo likes this.
  10. tonycluedo

    tonycluedo New Member


    Thanks spinlondon, I followed your suggestion above and it sorted out the problem I had with light switches being mixed up and some lights not working.
  11. JP.

    JP. Screwfix Select

    laughing-smiley-014[1].gif

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