smorgasbord said:
One thing that I noticed when visiting the UK is that they don't have power outlets in bathrooms. Because 240 volts and water is a dangerous combination.
..
The (post WW2) UK electrical standards are a mess and recovering only slowly, nothing to do with voltage. Their economy was in tatters, so all the standards, not just for wiring, were made to be frugal on resources. That is also why the fuses are in plugs .. so that wiring lenghts are not limited in the economy "circle" wiring designs used. *)
As for no power at bathrooms, that is related to no GFCI being required /up until recently/. GFCI is a must for a safe outlet
in a wet setting OR if grouding is not reliable. European wiring in cities used shared-ground (TN-C) and 2-wires only that allow for good safety without GFCI at the cost of needing multiple houses to pitch-in for that reliable ground. The limitation is that this does not work good-enough in a wet setting /dryer falling in a tub style/. So electric appliances were just not used in bathrooms.
That said, 110V + water
will kill you as efficiently as 230/240V + water will .. unless your heart can do 50/60 rpm. The advantage of the lower voltage is
only in a dry setting. Even then it is questionable. Do not look at 120V as something "safe" to touch.
The actual safe voltage for AC is much lower - in the 24V-48V range. In a wet/conductive setting, even 24V AC can kill. In a dry setting, the safe voltage for AC is only 50V, though 24V AC is the max widely used. For good reasons. Anything above 50V AC is in the "high voltage" safety category. For good reasons. It does not really matter if 120V or 400V, the mechanism in how it is dangerous is the same up to about 1000V. It kills by having your heart do 50 rpm, not by burning. DC does not do that.
What gets people confused is the safe
DC voltage *is* up to around 120V. This is why it was chosen when Edison made his US networks, they
were safe. Because they were 120V
and DC. Not anymore.
Once the original Edison-style DC grids were switched to AC, the safety went away, yet the disadvantages of a low voltage stayed .. I guess it was just tolerated post-WW2 simply because US was truly rich during the period, so the wasting on Copper was not a big-enough issue. And once the country was electrified, it became impossible to change/fix.
EDIT:
In a dry setting, the "safe voltage" for AC is 50V, not 60V as wronly remembered .. derives from human skin resistivity and minimum current for heart arrest, or something along those lines.
*) Czechoslovakia had similar issues - copper had to be imported which was frowned upon - here we addressed it by widely using aluminum wiring in new concrete/brick constructions /where it can be done safely/, "releasing" copper for wiring old houses. This results in old mud-brick houses wired in 1960/1970s having better wiring than new-built houses from the same periods. No much to burn inside a concrete/brick wall, unlike in a half-wooden house from 1800s.