No neutral wire for lightswitch

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  • No neutral wire for lightswitch
  • cranberry
    Member

    So, I want to fit some smart light switches, have taken out the old switches and found that there is no neutral wire supplied to the switch sockets. What is the best/easiest way to sort this and get a neutral supply to the switch ?

    trail_rat
    Member

    Why do you need a neutral ? It will be a switched live circuit.

    Flaperon
    Member

    Is your smart switch actually switching the live, or is it a remote? If the former you’ll need to run a three core and earth cable from the fitting (or a convenient junction box); if the latter then you’ll be able to repurpose the switched live as neutral.

    cranberry
    Member

    The smart switch has wifi, and connects to Amazon Echo, therefore it uses power and requires a neutral wire, according to the manufacturers.

    “6: The switch must be powered up through Lin (Live input) and Nin (neutral input). While Lout is Live output.”

    the switch

    footflaps
    Member

    The smart switch has wifi, and connects to Amazon Echo, therefore it uses power and requires a neutral wire, according to the manufacturers.

    Same problem I had when I put in a smart thermostat, had to run a new 4 core cable to replace the 2 core switched live one, PITA as it involved taking up floorboards etc. Worse for a light switch if it’s in a wall, as you’ll need to re-plaster over the new cable….

    cranberry
    Member

    I was hoping to avoid that sort of thing, got the smart switch because the switch location was chosen by someone who could see in the dark, around a corner and had an extra joint in their forearm. Also I don’t have floorboards – it is a concrete walled building.

    nickjb
    Member

    As Flaperon said, is the box actually doing the switching as well, ie does it need neutral, live and then a switched live to the item being switched on/off? If the switching is done elsewhere with another device then you could shuffle the wiring around at the ceiling rose but I suspect it does do the switching so you’ll need another core. If the existing 3 core cable is in oval conduit you might be able to use it to pull a bit of 4 core through instead but you’ll need access to the void probably by lifting the floor above. If not then things are about to get messy. Whatever you do make sure the neutral comes from the same circuit. Borrowed neutrals are dangerous.

    Edit: just seen the update. Probably just as easy to move the switch to the proper location. Similar amount of work and you end up with a proper solution

    Premier Icon nickdavies
    Subscriber

    You need to add the neutral into the switch, no easy way of doing it really you just have to do it properly and rewire the lighting to give neutral at the switch. Lot of work for a smart switch, be as easy just to fit a switch in the right place.

    You essentially need a dimmer switch for uk lighting, as the small residual current powers the switch. A proper on off switch can’t power itself from the circuit. Easiest would be send your switches back and get wifi dimmer switches – they’re not cheap at about £35 each but a lot less than it’s going to cost to redo the circuit.

    Or, even easier and will work with Alexa forget the switches and fit wifi bulbs.

    hammyuk
    Member

    There is an “easier” way although bein STW you’ll be told your house will burn down and baby robins will die….

    leebaxter
    Member

    You may be able to get a sonoff switch for what you are trying to achieve. I love them, they are cheap, and you can switch just about anything by wifi/alexa etc.

    hammyuk
    Member

    You “should” have a 3 core flex in the switch.
    A live in, switched live back up to the rose and an earth.
    Obviously the correct way is a new 4 core flex to add the neutral.
    Assuming you aren’t planning on selling the house any time soon and/or with the new remote kit in place then just use the earth as a neutral.
    It’s only there for the metal back box and isn’t really necessary as it is earthed to the building fabric anyway.
    Sleeve it with the appropriate colour and save a shit load of mess.

    Premier Icon leffeboy
    Subscriber

    Sleeve it with the appropriate colour

    an electrician did this in my house (Belgium) with the sleeving. Got signed off as well. Don’t know what the UK is like for that though

    Premier Icon molgrips
    Subscriber

    You “should” have a 3 core flex in the switch.
    A live in, switched live back up to the rose and an earth.

    Sure about that? That’s not what I was told.

    footflaps
    Member

    You “should” have a 3 core flex in the switch.
    A live in, switched live back up to the rose and an earth.

    Certainly the standard way of wiring a light switch. Sold all my regs docs after finishing the workshop, so can’t check…

    Premier Icon nickdavies
    Subscriber

    That’s standard uk wiring, common, switched live and earth. Since late 60’s/early 70’s I believe? Anything without an earth now must be due a rewire as it’s going to be pushing 50 years old.

    Premier Icon captain_bastard
    Subscriber

    3 core flex as above is indeed the standard arrangement for switches (some old houses and very latest aside)

    Nothing stopping you from using the earth for the N, providing the switch is a class 2 earthed device (plenty of older houses without earth to light fitting rely on this)

    Premier Icon molgrips
    Subscriber

    I thought the supply goes into the rose, then a live down to the switch and back…

    please don’t use the earth as a neutral ! The continuity of the earth is pretty important in any circuit! Regardless if the earth can or can not be connected to a back box or switch! Most installs will be in T&E lower diameter cable for the earth! Not insulated in the same way as live an neutral conductors!

    Take some advice from an electrician, don’t use the earth as a neutral!

    cranberry
    Member

    Sadly there is only a single cable going into the socket – Dutch 1972 standard of “what is the least we can do and get away with it”.

    mudmuncher
    Member

    Buy a smart bulb instead?

    bigfoot
    Member

    I thought the supply goes into the rose, then a live down to the switch and back…

    all the sparkys i know run the supply to the switch

    @molgrips That was deemed good practice 🙂

    @bigfoot Yeah that’s right now days 🙁 I still can’t believe they do it this way. Not unsafe and pretty useful in a modern domestic but in my eyes wrong wrong wrong. I guess it’s a generational thing.

    hammyuk
    Member

    Supply to switch is how it’s been done everywhere else BUT the uk for a long time.
    Only here do we have the archaic practice of T&E, ceiling Rose, etc.
    Conduit, single EQUAL conductors, modular switches , schukos and more make the uk way behind.
    Let’s not get started on the 3 pin plug….
    Or ring manis…

    cranberry
    Member

    The 3 pin plug is a wonderful thing.

    clicky

    Oi leave the Ring Final circuit out of it lol. But seriously U.K. behind because we have different practices?

    Premier Icon molgrips
    Subscriber

    That was deemed good practice

    So it’s changed? Seems a pretty risky thing to change…. but then, it seems people don’t know how it works anyway so I guess it makes no difference 🙂

    So if there is a live feed to the switch, is there a spur off the wiring in the ceiling void then or what?

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