"Owain Lastname" wrote in message
...
On Friday, 9 April 2021 at 19:07:39 UTC+1, Clive Page wrote:
The problem was that the ring-main fuses had to be larger and so the
system wasn't as safe.
The solution was to put a fuse in each plug-top and this made them much
larger. Does that
sound a reasonable explanation?

Not quite.

There were lots of small appliances intended for use on 2A
and 5A plugs, with thin flexes. And because there weren't
many sockets, a lot of those appliances had long leads.
Long, thin leads aren't adequately protected by a 30A
fuse, so fused plugs were necessary.

Doesnt explain why all other countrys
handle those fine without fused plug tops.

There is a secondary purpose to the fuse - it limits 13A
sockets to 13A max load, thus reducing high point loads
which would unbalance the ring. With unfused plugs a
naughty person would be able to plug their cooker into
the ring circuit. In the unfused round-pin days there were
hosts of adapters allowing table lamps to be plugged into
15A sockets without fusing. For some reason BS1363 doesn't
require 2-way adapters to be fused, and used not to require
3-way adapters to be fused either but this has now been changed.

what about mainland Europe - do they use ring mains with
their fuse-less plugs or does each socket have a separate
run back to the fuse-box? I have never thought to enquire.

They usually use 16A or 20A radial circuits, and modern
appliances have thick (or short) enough flexes that they
are adequately protected by a 20A MCB.

Thats wrong with the flex claim.