On 09/04/2021 19:07, Clive Page wrote:
I just watched another of Tim Hunkin's excellent videos - this one is on
connectors:

https://www.youtube.com/watch?v=q43tZ6DjuIE

One of the connectors he deals with is the UK 13A power plug.Â* He claims
that it was introduced in about 1947 because of the copper shortage.
The reasoning is that there was a post-war housing boom - I expect that
a lot of existing houses also needed re-wiring - but that the
conventional way of doing this by running a cable from the fuse-box to
each separate mains socket was deemed wasteful of copper.Â* So someone
invented the ring-main which generally used less cable.Â* The problem was
that the ring-main fuses had to be larger and so the system wasn't as
safe.Â* The solution was to put a fuse in each plug-top and this made
them much larger.Â* Does that sound a reasonable explanation?

In fact I can just recall the old 15 amp 3-pin plugs which preceded them
and I don't think they were all that much smaller even though they were
fuse-less.Â* In North America they don't seem to worry much about safety
given their lower mains voltage, but 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?Â* I have never thought to enquire.



The ring main certainly saved wire as more and more sockets were fitted.
It also gave two paths to each socket - did Hunkin mention that?

The 3-pin round-pin domestic plugs were 15A, 5A and 2A, IIRC.
Volume-wise the 13A is not that different.

The US domestic systems do have 220v capability - so they're not that
different from us.

PA