Guys,
Sorry I've only just seen this thread -- Been busy on a project this week and not had a lot of spare time.
The bathroom shaver outlets have an isolation transformer which is normally rated for about 20 to 30 watts maximum. That's enough for a shaver (obviously!), electric toothbrush, chargers for the battery versions of these, a small radio, etc. but certainly not enough for a hairdryer or other larger appliance.
The normal British 240V supply has one side grounded, which means that if you touch the "hot" side while simultaneously being in contact with something which is grounded (such as a bathtub), you will get shocked. Although the shaver output may still be 240V, the transformer provides an isolated supply which is not referenced to ground in any way. That means that contacting one side of the shaver outlet while being grounded will
not result in a shock. The only way to get hit is to simultaneously touch
both sides of the supply, which is much less likely to happen. It's that isolation from ground which provides the safety benefit.
That said, however, the IEE (Institute of Electrical Engineers -- The body which is responsible for Britain's electrical code) has really been quite paranoid about this for many years. In most European countries the local codes permit normal outlets in bathrooms, subject to them being suitably placed away from tubs and showers, and I certainly have no problem with a sensibly-located receptacle in a bathroom.
At least one benefit of the isolation transformer is that it is then easy to tap the winding for lower voltages as well. As some of you have noted, many (but not all) shaver outlets provide a 120V option for visitors, either by plugging into a different receptacle or by flipping a switch. These "United Nations" shaver panels also generally have sockets which will accept various combinations of British, European, American, and Australian plugs.
I find it very interesting the way UK wall sockets have on/off switches, so you don't automatically have a live current coming through when you don't need it. (Well, I've only noticed this in the flat where I'll be living; don't know if it's like that all over the UK.)
Switched outlets are pretty much the norm here, although only because it's what people have come to expect. There's nothing in our electrical code which requires the switches. Unswitched outlets are still sometimes used in places such as under a kitchen worktop for a washing machine, and in similar situations.
And how long did it take you to figure out that the switches work upside-down?
While on the subject, it's also a common misconception here that our IEE Wiring Regulations require the use of a pull-cord for a bathroom lightswitch. The only restriction on using a normal wall switch is that it must be out of reach of anyone in the tub or shower. (Admittedly in some of our postage-stamp sized bathrooms such placement would be impossible.)
It's also worth pointing out that as far as residential wiring is concerned, there is no legal requirement to follow the IEE code anyway. There are some new rules which came into force this year which have affected wiring, but that's a whole different thorny subject.
