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    Light Switch - connection


    I have removed my down stairs light switch (for decorating) which controls the upstairs light. I have 3 wires - 1 x Black 2 X red Does Black go in the top (Common) and the 2 reds in the bottom? There's also a switch upstairs. I should of taken a picture - but didn't.

    Asked by Mark on 28th Mar 2022
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    Best Answer

    Andrew cogbill Electrician

    "Have a look at the switch upstairs. I would imagine that one of the reds would go on the bottom in one of the terminals and the black in the other. The remaining red would go into the common.

    But again have a look at the upstairs switch. I’m assuming this is a two way light switch, ie it can be operated in two positions."

    Answered on 28th Mar 2022 - Member since Mar 2022 - report

    "Normally yes black goes to the common and other two reds to l1 and l2. To make sure, you have to find live cable. After you find live one, you should go to upstairs and press the button once and then go downstairs again and check which one is live. İf the same cable still live that one goes to common. İf the live one changed after you pressed the button at upstairs both live cables (first live before you press the upstairs button and second live after you press) goes to L1 and L2"

    Answered on 10th May 2022 - Member since Feb 2022 - report
    WK Electricals Ltd

    "These cables are called Strappers.
    Ensure to link the black in the common to the black in the common of the other switch and l shall test continuity with a test metre they are linked together with a brown sleeving on both necks since they come as switch live cables.
    Also ensure to link the red in L1 (left hand side of switch to same position on other switch. Then other red cable interconnected to both switches to the right hand side. I shall confirm with continuity check metre.
    As these switches are being tested flip switches on and off to hear belling at one end and alternate switches"

    Answered on 28th Apr 2022 - Member since Jun 2021 - report
    Watson Brown Electrical Services

    "If it's wired in twin and earth then 1 red and the black are strapers which go in the bottom and the other red maybe is common..if it's in singles then any could be any and you need a continuity tester. Also, see in the light where the wires are thing may be get a photo of the wires in the light which could help"

    Answered on 1st Apr 2022 - Member since Dec 2021 - report
    Vk handyman

    "the black one on top (com) connection reds bottom connection (L1 and L2)"

    Answered on 11th Apr 2022 - Member since Apr 2022 - report
    GabyEnergy Ltd

    "Hi Mark. Before you do any work please isolate wires by cutting the power completely. Open the switch upstairs and check how the wires are done, then you need to do the same downstairs"

    Answered on 28th Mar 2022 - Member since Jan 2021 - report
    M electrical&SON

    "Look at switch top off stairs to confirm which colour goes in the common please switch power off first"

    Answered on 28th Mar 2022 - Member since Dec 2020 - report

    "Hi Mark,
    The 1 black wire and 1 of the reds are strappers which are connected to the bottom of the switch and the other red into the top which will be a permanent live. If you have any way of testing the cables to see which 1 is permanently live, If not try it by trial and error if the 2 way does not work properly just swap the reds around. Please make sure you isolate the lighting circuits before attempting any of this work"

    Answered on 29th Mar 2022 - Member since Mar 2022 - report

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