gkenyon:
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 ?

A very good question!


Yes - I have thought of it (with some worry), and have wondered how many manufacturers give it a moment's thought and what standards there are for this case.  The last time was just last weekend, when I got a new wifi box whose adaptor gave a choice of a UK or Euro plug end to clip onto it.  I wondered how many manufacturers realise that in contrast to the Euro plugs, which are likely to have 10 A to 16 A protection probably by a good fuse or an MCB, the UK socket might even have 45 A protection (extreme cooker-socket) or a BS3036 fuse. The BS1363 standard grew up at a time when everything could be expected to have a fused plug.  I'm not aware of any other system in the world that has such high current.  

(I don't have access to BS3036 .. is a maximum let-through specified? It would amaze me if it's not a good deal higher in the 'hundreds to thousand-or-two' amps range, compared to modern MCBs or good [shaped element and sand] fuses).


Overload doesn't seem very important: even 3A plug fuses aren't a serious overload protection for small electronics.  Most 'wall wart' adapators I've seen don't even have a metal PE pin, so high L-PE currents wouldn't arise.  But L-N short-circuit faults such as condensation and tracking, a flying lead from a plug pin breaking at the solder and touching the others, etc, don't sound nice.  I'd not feel too bad about a B or C MCB of 32 A, but worse about the BS3036 fuses.  I accept it's unlikely that these events would happen, and likely they could blow themselves out without much damage beyond the plastic box. But I seriously wonder whether even reputable manufacturers supplying the UK realise the conditions.  If anyone would have a good idea of what requirements there are in standards covering wall warts, I think you would!  (I'm often impressed by your standards awareness): is there anything that covers all such devices and requires suitable tolerance of high protection settings? That would be comforting.

 

gkenyon:
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 ?

A very good question!


Yes - I have thought of it (with some worry), and have wondered how many manufacturers give it a moment's thought and what standards there are for this case.  The last time was just last weekend, when I got a new wifi box whose adaptor gave a choice of a UK or Euro plug end to clip onto it.  I wondered how many manufacturers realise that in contrast to the Euro plugs, which are likely to have 10 A to 16 A protection probably by a good fuse or an MCB, the UK socket might even have 45 A protection (extreme cooker-socket) or a BS3036 fuse. The BS1363 standard grew up at a time when everything could be expected to have a fused plug.  I'm not aware of any other system in the world that has such high current.  

(I don't have access to BS3036 .. is a maximum let-through specified? It would amaze me if it's not a good deal higher in the 'hundreds to thousand-or-two' amps range, compared to modern MCBs or good [shaped element and sand] fuses).


Overload doesn't seem very important: even 3A plug fuses aren't a serious overload protection for small electronics.  Most 'wall wart' adapators I've seen don't even have a metal PE pin, so high L-PE currents wouldn't arise.  But L-N short-circuit faults such as condensation and tracking, a flying lead from a plug pin breaking at the solder and touching the others, etc, don't sound nice.  I'd not feel too bad about a B or C MCB of 32 A, but worse about the BS3036 fuses.  I accept it's unlikely that these events would happen, and likely they could blow themselves out without much damage beyond the plastic box. But I seriously wonder whether even reputable manufacturers supplying the UK realise the conditions.  If anyone would have a good idea of what requirements there are in standards covering wall warts, I think you would!  (I'm often impressed by your standards awareness): is there anything that covers all such devices and requires suitable tolerance of high protection settings? That would be comforting.