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Ever thought about ... ?

gkenyon
I was asked a series of interesting questions this week about fault protection and overload protection for a particular application. Some of these really make you think, and the physics doesn't always lead you where you think you'd go.


Dropping out of all this, was me pointing out something interesting which I wonder whether it's ever crossed the minds of contributors to this Forum ... so here goes.


Ever thought about what, in typical UK installations, protects the electronics in a plug-in [to a standard BS 1363-2 socket-outlet] phone charger / wall-wart type power converter against:

(a) Fault current (consider both cases of L-N and L-PE); and

(b) Overload current ?




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    Simon Barker:
    Sparkingchip:
    Sparkingchip:

    What sort of question is that to ask of a guy with a lightning charger lead dangling over the arm of the settee immediately next to him?


    Being an Ipad lightning lead the terminals are exposed to touch and every so often I feel a tingle when I put by bare elbow on it, guess what it is plugged into?



     




    So the worst that can happen is?




    If it's a genuine Apple charger, then the worst that can happen is a small tingle.  It's part of the way they are designed, with a class Y capacitor between the AC and DC sides.  That can leak a tiny current across.


    If it's a cheap charger of unknown origin, then the best place for it is the electronics recycling bin.




    Interesting ... does that align with the Ethernet standard ... particularly if the device is connected to a wired connection.


    I really worry about devices that are connected to Class II power supplies on the mains side, and then connected via conductive cabling to other devices. Far happier with my laptop with a PELV (functionally earthed) secondary.


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  • 0
    Simon Barker:
    Sparkingchip:
    Sparkingchip:

    What sort of question is that to ask of a guy with a lightning charger lead dangling over the arm of the settee immediately next to him?


    Being an Ipad lightning lead the terminals are exposed to touch and every so often I feel a tingle when I put by bare elbow on it, guess what it is plugged into?



     




    So the worst that can happen is?




    If it's a genuine Apple charger, then the worst that can happen is a small tingle.  It's part of the way they are designed, with a class Y capacitor between the AC and DC sides.  That can leak a tiny current across.


    If it's a cheap charger of unknown origin, then the best place for it is the electronics recycling bin.




    Interesting ... does that align with the Ethernet standard ... particularly if the device is connected to a wired connection.


    I really worry about devices that are connected to Class II power supplies on the mains side, and then connected via conductive cabling to other devices. Far happier with my laptop with a PELV (functionally earthed) secondary.


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