Mike wrote:
The view of a friend working for the EU directorate on this matter in the
mid-90s was roughly as follows :
The UK plug/socket is dangerous and probably causes more electrical fires
than any other piece of electrical equipment.
Poorly fitted *plugs* were certainly a major concern, but hasn't that
been addressed by plugs fitted on appliances before sale?
From what I've seen of European plugs they're not very substantial
either, those with cord outlets parallel to the pins are vulnerable to
being pulled out of sockets by the flex, and they're not polarised, so
their ES lampholders can have either contact live.
Similarly although the IEE have done well getting ring mains systems safe,
it is felt they rely on diversity too much for a modern house where there
may be large numbers of high current consumption devices often in separate
rooms where the users do not realise they are using a common ring. Also the
allowed practice of adding almost uncontrolled numbers of extra sockets to a
ring makes this worse. It is accepted that UK house make far less use of
electrical heaters than some other countries due to our cheap supply of gas
but pointed out that this won't last indefinitely.
However the ring was never designed for supplying fixed heating, and
if/when gas runs out we're going to be stuck for cheap electricity. For
safety reasons, if the main gas supply network fails, the bulk consumers
of gas (the electricity generators) are taken offline first, rather than
disconnecting domestic consumers.
The growth in number of sockets required is mostly consumer electronics,
which are low-current appliances. The ring was also never designed for
the large number of high-current kitchen appliances we see, but that is
being addressed by the provision of a separate circuit for the kitchen.
The proposed EU recommended wiring system consists of separate feeds to each
room with a small CU in that room with a breaker for lights and one for each
group of sockets/piece of equipment. The best CUs actually fit under the
light switch by the door which hinges up. A simple look round the room will
soon tell you if you are taking too much current (and the much more likely
to be correctly rated trip in that room blows anyway - not taking out the
whole house as in the UK). This is not to say that any particular country
in the EU follows this approach to the letter today.
Which still means (if you have 20A circuits) that some combinations of 2
x 3kW heaters, in some or other sockets on the same or different
circuits, will or won't work. The advantage of the ring circuit is the
flexibility it gives for using appliances without worrying which socket
they're plugged into. That's based on diversity, which is a sound
engineering principle.
One of the main advantages of the ring circuit, designed for the
post-war housing needs, was that it used less material than lots of
separate radials. Presumably the "proposed EU recommended wiring system"
is supported by European consumer unit and cable manufacturers, but I
doubt if by anyone else.
Why would this arrangement have a "much more likely to be correctly
rated trip"? And UK trips (do you mean MCB or RCD?) don't take out the
whole house in a correctly designed installation. Whole-house RCDs are
deprecated.
Owain
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