On 09/04/2021 18:45, Peter Able wrote:
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.
So someone invented the ring-main which generally used less cable.
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.

From a pedantic POV, the USA has 120V between live and neutral. It can
also have 240V or 208V depending on the supply. 208V being from 2 legs
of their 3-phase supply.