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Using an earth as a neutral for a photoelectric switch?

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  • 10-04-2020 5:28pm
    #1
    Registered Users Posts: 11,758 ✭✭✭✭


    its most probably a big no, no but will ask anyway. I want to wire up a 230vac
    photocell to a switch in the hall.

    The switch has only 2 lives (Live & Switched live) and an earth attached on the metal back box. there's no neutral at the light-switch box / patress at the back of the light switch and I don't fancy chasing the wall to put a neutral in.

    Is it possible to use the earth on the metal back box as a neutral, seeing as over here we use a TN-S here in Ireland?

    I used to see a smiths photocell light switch years ago that replaced a normal light switch and i wonder how they got on without using any neutral ?

    Thanks for info.


Comments

  • Registered Users Posts: 4,733 ✭✭✭meercat


    its most probably a big no, no but will ask anyway. I want to wire up a 230vac
    photocell to a switch in the hall.

    The switch has only 2 lives (Live & Switched live) and an earth attached on the metal back box. there's no neutral at the light-switch box / patress at the back of the light switch and I don't fancy chasing the wall to put a neutral in.

    Is it possible to use the earth on the metal back box as a neutral, seeing as over here we use a TN-S here in Ireland?

    I used to see a smiths photocell light switch years ago that replaced a normal light switch and i wonder how they got on without using any neutral ?

    Thanks for info.

    Definitely not. Can you fit a recessed sensor beside your existing ceiling fitting or get a fitting with one built in. Leave the switch permanently on.


  • Moderators, Home & Garden Moderators, Technology & Internet Moderators, Regional East Moderators Posts: 12,544 Mod ✭✭✭✭2011


    ^^^ Agree.

    Apart from being against the rules this is not safe.


  • Registered Users Posts: 11,758 ✭✭✭✭Andy From Sligo


    meercat wrote: »
    Definitely not. Can you fit a recessed sensor beside your existing ceiling fitting or get a fitting with one built in. Leave the switch permanently on.

    Thanks , i will have to rethink if thats the only way. The 3 GU10 spotlights are outside and the switch inside and i didnt really want to wire up the photocell outside if I could have helped it but just have the photocell rely on the daylight coming in and out of the hall and front door windows to switch it on and off.


  • Registered Users Posts: 2,567 ✭✭✭Risteard81


    here we use a TN-S here in Ireland?

    It's TN-C-S (not TN-S). Terra/Neutral Combined & Separate. Combined in the DSO's PEN conductor and then separate within the consumer's installation.

    But no, your proposal is incredibly dangerous and illegal.


  • Registered Users Posts: 11,758 ✭✭✭✭Andy From Sligo


    Risteard81 wrote: »
    It's TN-C-S (not TN-S). Terra/Neutral Combined & Separate. Combined in the DSO's PEN conductor and then separate within the consumer's installation.

    But no, your proposal is incredibly dangerous and illegal.

    ah right, thanks.

    Would you have an idea how the old smiths photo-electric switches that used to replace a 1 gang, 1 way switch used to work without a neutral by any chance?


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  • Registered Users Posts: 11,758 ✭✭✭✭Andy From Sligo




  • Closed Accounts Posts: 13,422 ✭✭✭✭Bruthal


    I used to see a smiths photocell light switch years ago that replaced a normal light switch and i wonder how they got on without using any neutral ?

    They work by using the current powering the bulb, and when it is off, they still allow a small current through the bulb, to operate the switch electronics.
    says not to use with LED lights though and the lights in the porch are 3 GU10 LED lights


    Leds might give problems, either being too low a load to power the switch electronics, or may still glow when the switch is in the off state.


  • Registered Users Posts: 11,758 ✭✭✭✭Andy From Sligo


    Bruthal wrote: »
    They work by using the current powering the bulb, and when it is off, they still allow a small current through the bulb, to operate the switch electronics.

    Leds might give problems, either being too low a load to power the switch electronics, or may still glow when the switch is in the off state.

    ah right , thank you . that's very helpful advice/reply. the LED's are 3 x 5w GU10


  • Closed Accounts Posts: 305 ✭✭kramer1


    Get a few WiFi enabled gu10s and set them for dusk Dawn?


  • Registered Users Posts: 73,397 ✭✭✭✭colm_mcm


    Are you even allowed to do changes like that, it’s a council house you have isn’t it?


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  • Registered Users Posts: 11,758 ✭✭✭✭Andy From Sligo


    kramer1 wrote: »
    Get a few WiFi enabled gu10s and set them for dusk Dawn?

    ah right , interesting - I shall look into that thanks


  • Closed Accounts Posts: 305 ✭✭kramer1


    ah right , interesting - I shall look into that thanks

    Robus do some half decent ones at a reasonable price, no hub needed


  • Registered Users Posts: 77 ✭✭greenore


    What exactly are you trying to achieve here? Can you not wire photocell from light fitting if you have permanent live, switched live & netural at the first fitting?


  • Registered Users Posts: 11,758 ✭✭✭✭Andy From Sligo


    kramer1 wrote: »
    Robus do some half decent ones at a reasonable price, no hub needed

    interesting , have you any idea of price - even roughly?

    just been reading the spec sheet , controlling would be done on a timed scenario then, rather than come on when dark and go off when light then . So with the app, tell it to come on at say 9pm and go off at dawn time say?

    would be more handier than getting someone to wire in a switch or photocell

    or I could do what I have been doing and switching them on and off manually at the switch ... (or leaving them on all the time!) :)


  • Registered Users Posts: 11,758 ✭✭✭✭Andy From Sligo


    greenore wrote: »
    What exactly are you trying to achieve here? Can you not wire photocell from light fitting if you have permanent live, switched live & netural at the first fitting?

    I haven't removed the switch. But I am presuming it only has 2 lives and a neutral there like all light switches normally have


  • Closed Accounts Posts: 305 ✭✭kramer1


    interesting , have you any idea of price - even roughly?

    just been reading the spec sheet , controlling would be done on a timed scenario then, rather than come on when dark and go off when light then . So with the app, tell it to come on at say 9pm and go off at dawn time say?

    would be more handier than getting someone to wire in a switch or photocell

    or I could do what I have been doing and switching them on and off manually at the switch ... (or leaving them on all the time!) :)

    About a tenner plus vat a piece, should have a dusk Dawn automation on the app that turns on or off when the Internet tells the bulb that it's sunrise or sunset in your part of the world. I have them but haven't really played around with the settings. Probably easier than rewiring


  • Registered Users Posts: 11,758 ✭✭✭✭Andy From Sligo


    kramer1 wrote: »
    About a tenner plus vat a piece, should have a dusk Dawn automation on the app that turns on or off when the Internet tells the bulb that it's sunrise or sunset in your part of the world. I have them but haven't really played around with the settings. Probably easier than rewiring

    thanks, just as you were writing I saw them on this site

    https://xpresselectrical.ie/product-category/lamps/led-bulbs/led-gu10/

    €13.90 inc. VAT each.

    But when shops back open as normal I will try Cliffords and homebase in sligo . see if they do them.

    Thanks a lot for alerting me to them. thats good then that it will work for dawn to dusk as well, brilliant. - and thats good also they are tune-able from warm white to cool white.

    I knew you could get the large normal type wifi bulbs , but I didnt know you could get GU10 in it until you mentioned it cheers.


  • Closed Accounts Posts: 305 ✭✭kramer1


    thanks, just as you were writing I saw them on this site

    https://xpresselectrical.ie/product-category/lamps/led-bulbs/led-gu10/

    €13.90 inc. VAT each.

    But when shops back open as normal I will try Cliffords and homebase in sligo . see if they do them.

    Thanks a lot for alerting me to them. thats good then that it will work for dawn to dusk as well, brilliant. - and thats good also they are tune-able from warm white to cool white.

    I knew you could get the large normal type wifi bulbs , but I didnt know you could get GU10 in it until you mentioned it cheers.

    No bother


  • Registered Users Posts: 77 ✭✭greenore


    I haven't removed the switch. But I am presuming it only has 2 lives and a neutral there like all light switches normally have

    Light switches dont normally have a Neutral

    Forget about switch, you may be able to connect photocell via wiring at LIGHT FITTING.... depends on what way it was originally wired


  • Closed Accounts Posts: 13,422 ✭✭✭✭Bruthal


    I have garden floodlight that comes on when i open the shed or sliding back door.

    In the setup I have a lightwaverf relay set to close its contacts at dusk, and open at dawn. So it keeps track of the changing times.

    I have sonoff relays as well, which can also do the same.

    Fit one of the sonoff ones up at the lights, and that will work assuming you have wifi coverage where you put it. You can then also check if the light is on or off with phone, or switch it on or off with phone. Leave wall switch on, change to a key switch possibly.


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  • Moderators, Home & Garden Moderators, Technology & Internet Moderators, Regional East Moderators Posts: 12,544 Mod ✭✭✭✭2011


    +1

    Also you could consider using a Sonoff T4EU1C, see a thread on it here.

    This does not require a neutral and can be programmed as a timer from a free app. As Bruthal said wifi coverage is required. Alternatively it can be used with a lightwaverf relay as suggested. These units fit neatly onto a 1 gang box.


  • Registered Users Posts: 11,758 ✭✭✭✭Andy From Sligo


    Bruthal wrote: »
    I have garden floodlight that comes on when i open the shed or sliding back door.

    In the setup I have a lightwaverf relay set to close its contacts at dusk, and open at dawn. So it keeps track of the changing times.

    I have sonoff relays as well, which can also do the same.

    Fit one of the sonoff ones up at the lights, and that will work assuming you have wifi coverage where you put it. You can then also check if the light is on or off with phone, or switch it on or off with phone. Leave wall switch on, change to a key switch possibly.

    Thanks, some of that is double dutch to me but i will check them things out and see what they are about thanks


  • Moderators, Home & Garden Moderators, Technology & Internet Moderators, Regional East Moderators Posts: 12,544 Mod ✭✭✭✭2011


    ^^ It would be best to get an electrician to do this if you are not 100% sure of what to do.


  • Registered Users Posts: 11,758 ✭✭✭✭Andy From Sligo


    2011 wrote: »
    ^^ It would be best to get an electrician to do this if you are not 100% sure of what to do.

    yes, that or just carry on turning on and off the lights at the lights switch like i have been doing. - its no big hassle i suppose :)


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