Hi Belgian, and welcome to ECN!
I think C-H (he's in Sweden) has summed up the situation here in Britain fairly well.
The most widely used residential arrangement for receptacles is the ring circuit, fed from a 30 or 32A fuse or circuit-breaker. Our plugs then contain a cartridge fuse, the maximum rating of which is 13A. That's why polarity of wiring at the socket is considered so important here, because if you swapped the line and neutral then the fuse in the plug would be in the neutral line.
You'd be left with the 30 or 32A fuse at the main panel as the only protection against shorts to ground. For most appliances the actual polarity of supply on the cord is unimportant, and these days you'll find the same model sold right across Europe with just a different plug.
In TT systems there is a main RCD (GFI) which would obviously provide ground-fault protection in this situation. Although RCDs are becoming increasingly common in TN systems as well, they are not required, and therefore with reversed polarity you could end up with a 0.5 or 0.75 sq. mm cord having no better protection than a 30A fuse.
I have heard from somebody that in
England, it is not the neutral which is grounded at the supply
No, all public supplies in the U.K. have been required to have the neutral solidly grounded since at least 1930. Except for a few remote houses which are fed from a single-phase 240V xfmr, practically all LV distribution is 3-phase. Officially the levels are now 230/400V, but in practical terms we are still nominally 240/415V.
Residential service is normally just 2-wire single-phase tapped from one phase and neutral of the 4-wire network.
See the diagrams
at this link to get a better idea.
I'm not quite sure I understand your terminology here. Do you mean a 230V delta system? Or maybe a 133/230V wye system without the neutral brought into the house?
By the way, I'm not sure how you tried to post the picture you referred to, but if have any problems feel free to e-mail me and I'll explain how to do it. Alternatively, e-mail the picture to me as an attachment and I'll post it for you.
[This message has been edited by pauluk (edited 10-10-2002).]
