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current light switch wiring regs?

  • 04-03-2025 09:27AM
    #1
    grimeire
    Registered Users, Registered Users 2 Posts: 423 ✭✭


    Just got a house recently fully rewired. all plaster board was removed so it was rewired from scratch.

    We have a couple of outside lights that i want to connect to the alarm/CCTV system so if the alarm goes off or the CCTV has alerts triggered then the lights will come on.

    To my surprise after getting a couple of smart switches none of the light switches in the house have a neutral wire. All they have is a live. Is it not regs to have a 3 core wire going to the lights/switches?

    As there is no neutral wire i can not replace any light switches in the house with smart ones since they can not be powered by live alone.

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Comments

  • #2
    Deagol
    Registered Users, Registered Users 2 Posts: 1,838 ✭✭✭Deagol


    I don't know the answer - but didn't you think to ask that question before the rewire was done?

    I know my house built in 2000 has neutrals and both switched and unswitched live at all light fittings. So I'm a bit surprised to see you don't. But perhaps rewires are exempt?



  • #3
    10-10-20
    Registered Users, Registered Users 2 Posts: 8,867 ✭✭✭10-10-20


    Hi, as far as I know there isn't a standard for wiring lighting, but there are two options for doing so - neutral at the switch or no-neutral. Neutral at the switch is more copper, effort and cost to install, so it's logically not always the chosen method unless you specify it.

    Your options for controlling lights are not too limited now as there are a number of devices which work with no-neutral setups. Some do require that a bypass component be added across the light, that's to allow some current to pass through the circuit when the lamp is switched off, but otherwise you should be able to work around it.

    Example of that setup with a suitable Shelly device is like this:

    image.png

    https://www.shelly.com/products/shelly-dimmer2

    Hope it helps!



  • #4
    grimeire
    Registered Users, Registered Users 2 Posts: 423 ✭✭grimeire


    https://www.boards.ie/discussion/comment/123229764#Comment_123229764

    i seen when he was doing first fix that all cables were single core. I assumed he was running individual neutral and live. I even asked why he was not running 3 core cables as it would be faster than running multiple cables for each core and he said its faster and easier with the second fix.

    The rewiring was not cheap at nearly 20k. needless to say im not happy. I just assumed with the regs there would have to be 3 cables.



  • #5
    grimeire
    Registered Users, Registered Users 2 Posts: 423 ✭✭grimeire


    https://www.boards.ie/discussion/comment/123229766#Comment_123229766

    trying to fit one of these on top of the light switch into a 25mm box along with all the cables is going to be a nightmare. Most of the lights are 2 or 3 gang so there are a few wires.

    Im a bit confused by the diagram as it shows a Neutral going into the module.



  • #6
    ted1
    Registered Users, Registered Users 2 Posts: 24,257 ✭✭✭✭ted1


    That’s the problem when you assume.

    You can get smart switches that don’t require a neutral.

    You can get smart lamps (bulbs) that’ll do the same as smart switches. The wiring diagram above illustrates this , it’s just a capacitor that will keep the circuit live when switches



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  • #7
    10-10-20
    Registered Users, Registered Users 2 Posts: 8,867 ✭✭✭10-10-20


    https://www.boards.ie/discussion/comment/123230002#Comment_123230002

    That neutral is on the far side of the light fixing in your case - it's just not brought into your switch back-box.



  • #8
    ptogher14
    Registered Users, Registered Users 2 Posts: 205 ✭✭ptogher14


    There's no regulation around having a neutral at a switch. Traditionally the majority of sparks would consider this bad practice. Although I do assume it's becoming more common given these devices are on the market. Apologies, I know this doesn't help your issue



  • #9
    Lenar3556
    Registered Users, Registered Users 2 Posts: 2,008 ✭✭✭Lenar3556


    Are smart switches a good idea? I have a lot of cases of them disconnected or faulty after relatively short periods.
    A PIR sensor light(s) might be a good solution?



  • #10
    meercat
    Registered Users, Registered Users 2 Posts: 4,908 ✭✭✭meercat


    https://www.boards.ie/discussion/comment/123229952#Comment_123229952

    single cables aren’t permitted. There should be an earth conductor



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