"Martin Bonner" wrote in message
...
Are US and European plugs capable of having a fuse fitted in them
No

or do
their appliances always blow the circuit (eg downstairs ring main)
What ring main? Everything is wired as (chained) radials. But yes,
the only fuse is in the consumer unit.

Are ring mains mainly a UK innovation, then? I hadn't realised that.

Either way, if an appliance develops a fault, it is normal that everything
fed by the same fuse or circuit breaker will fail, rather than (hopefully)
only that appliance failing and everything else staying on. Now THAT is a
colossal retrograde step: the thought that a short in a table lamp or a PC
power supply could disable my deep freeze when I was out and unable to
replace the fuse doesn't bear thinking about. I'm surprised that when we in
the UK went from unfused to fused plugs, other countries didn't see that
advantage and make the same change.

One of the few places where old unfused round-pin plugs are still used today
is in theatre/TV lighting where it's much easier to change a fuse on the
lighting board rather than one up above the stage where each light is
plugged into its circuit.



Do 240V and 120V bulbs have identical-sized screw threads, or are
they deliberately incompatible sizes to avoid putting a 120V bulb in a
240V fitting?
No idea, but I would guess from the name ("Edison") that they are
identical.

I think there are various different diameters of ES (maybe all with the same
pitch of thread) but I wonder if this is enforced so that bulbs that are
rated for different voltages can never be interchanged in the same light
fitting (ie to prevent you accidentally using a US bulb in European mains).
The real problem arises if you bring a US table lamp back to Europe and
simply change its mains plug - now you wouldn't be protected by the
diameter/voltage restirctions!