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Wiring 133/230Y System

Former Community Member
Former Community Member
Is there anything I need to consider when designing and wiring for this type of system? TN-S without the neutral distributed.
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    I don`t like Edison Screws!

    I find BC for lamps more positive .

    i.e. better at go/no go connections therefore less arcing/burning.

    Might be down to the poor quality of lamps and fittings in real life rather than the concept itself.

    However it is about time that BC were made to disconnect pins once lamp removed. I know you can buy them but they are not mainstream. I feel in that sense ES do give a bit more potential safety if wired correctly in UK because the Live  you are most likely to touch is the N rather than the Ph.

    All this uproar on "fatally flawed" website (which I wholly support) yet we still have the potential danger from BC table lamps and not much of a song and dance is made about that - OK there are not mounds of dead bodies littering our living rooms but the danger is till there.

    I fact - a few years back now - a youg teanager was killed around our way - the family blamed the council for the recent house rewire but this was ruled out so I think it was down to the CB table lamp she was using in the outside loo.
  • 0
    Now I've been reading g this thread i was tempted to check  the exposed metal parts on the colored 25 watt bulbs in my disco room would you believe it the outers are live 240 volts to earth. Fortunately this upstairs so shock risk reduced also the whole lot is fed via a p,ug in RCD due to the ancient wiring
  • 0
    Not something I am experienced with and I am never likely to be.


    I did do a quick bit of reading last night and that left me wondering what actually happens under first fault condition such as touching a single exposed conductor?
  • 0
    Do not fancy 133 volts to earth on the shell of an E27 lamp

    Any vaguely modern E27 holders don't have the outside contact really any more exposed than the centre one. Rather than the old system of the thread of the holder being metallic and connected to N, nowadays the holder's thread is insulating with a contact for the outer positioned at the base of holder alongside the centre one. The lamp cap itself is shrouded when in position - so it can't be touched when the lamp is screwed fully home, and when loosened is disconnected from both contacts before the cap becomes exposed. There's still the problem of an empty holder - but that's the same with the BC system.

        - Andy.
  • 0
    Sparkingchip:

    Not something I am experienced with and I am never likely to be.


    I did do a quick bit of reading last night and that left me wondering what actually happens under first fault condition such as touching a single exposed conductor?


    In principle, nothing different to when touching a single exposed conductor on a UK type 230/400 volt system. Except at a lower voltage.

    An electric shock at 133 volts would be received, less risky than at 230 volts but by no means benign.

    The usual precautions should be taken to avoid contact with live conductors.

    A suitable RCD would greatly reduce the risk of this shock being fatal.


    For a 2 wire circuit, a standard UK type TRUE TWO POLE RCD would be suitable.

    For a 3 wire circuit a special RCD intended for the lower voltage would be needed. These are readily available in countries that use 127/220 volt systems, the very similar 133/230 volts about which we are talking.


  • 0
    Do I use 0.8 seconds instead of 0.4 for my disconnection time?

    Table 41.1 puts the Uo boundary between 0.4s and 0.8s at 120V nominal - so as your Uo is 133V nominal (and TN), then by the book you should still be using 0.4s disconnection time for small final circuits (or 5s for socket circuits over 63A or other final circuits over 32A or any rating of distribution circuits).

       - Andy.
  • Former Community Member
    0 Former Community Member
    AJJewsbury:
    Do I use 0.8 seconds instead of 0.4 for my disconnection time?

    Table 41.1 puts the Uo boundary between 0.4s and 0.8s at 120V nominal - so as your Uo is 133V nominal (and TN), then by the book you should still be using 0.4s disconnection time for small final circuits (or 5s for socket circuits over 63A or other final circuits over 32A or any rating of distribution circuits).

       - Andy.





    I never understood that considering voltage at the fault point to remote earth will be lower.


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