So why aren't RCDs deemed safe enough to protect occupants in a bathroom with outlets over there? We have them all over the place here, and from all accounts they work reliably.
And what's wrong with wire nuts? Properly installed, I've never seen one fail.
How do y'all connect your wires, anyhow?
We use a lot of terminal strip (chocolate box) type connectors, also a lot of insulated crimp ferrule types are now being used and I expect this method will be the way forward due to speed of installation, cost and tamper resistance offered. Wire nuts were dodgy in the UK for several reasons. They were fragile and if not handled properly were prone to cracking, the thread was actually cut into the porcelain, so the slightest uneven wire joint caused threading and loosening problems leading to heating and eventually fire, especially anywhere that was affected by vibration. The ones now used in the US and Canada etc have the added benefit of having a wire spring internally for threading, however, again, if the wire joint isn't great to begin with, the new risk is that the wire spring then carries current causing heating, burning and fire. The later wiring types used for domestic wiring in the UK moved from stranded cable to solid core, making wire nuts a poorer match mechanically and electrically. The US has however persisted in using them despite this change in their own cables. I agree though, if a properly made, stranded wire joint is formed and a good quality wire nut is properly fitted, it is about as safe as any other method in use today, but using them on solid cored wiring or anywhere subject to ground vibration is a risk in my opinion
RCD's in the UK are regarded as a means of indirect contact protection, a supplementary line of defense if you will, they will also help protect against a number of other conditions occuring downstream, and will happily react to certain nuisance disturbances upstream, much to the dismay of many installers that get their circuit designs wrong. The problem is they can often fail silently and without the end user being aware of the failure, especially true when proper test procedures are not followed, therefore they should not be relied upon. They don't just need to trip, they need to do so within a set time period, so sometimes although the test button works, it just isn't tripping fast enough to ensure safety
We have a whole list of areas needing special protection in our regulations, a steamy bathroom being one such area. The human body resistance is often reduced from the many megohms of dry skin to just a few kilohms when moist, and much, much less, perhaps 500ohms or less if the skin is damaged, or indeed if an electical burn takes place following a shock. That's quite apart from the many soaps and salts etc found in bathroom products that may be on your hands or body at the time, reducing that resistance further still. In this case, even although the RCD may trip off at a lower current deemed safe when dry skin is involved, there is sufficient current flow to injure, or kill when the skin is moist, wet or damaged.
Quite apart from that, none of these devices, including outlets, switches, RCD's and pretty much most things aimed at domestic installations (without further means of IP protection, like covers, membranes etc) are rated for use in wet environments
As an aside, Pommie mentioned sinks and taps etc. There are no actual regulations on spacing devices such as outlets and switches etc away from water sources, however there are several best practise construction guidelines that go hand in hand with the regulations that suggest 1000mm from water sources where practical with a 300mm minimum distance being observed where there is no alternative. Exposed metal parts like sinks, taps and drainers etc should all be earthed (grounded) and an equipotential earthing system is employed to ensure that there are no potential differences between surfaces, also the supply must automatically disconnect when any fault is presented, usually achieved by the breaker for that circuit. Basically, the common sense (this is where the word competent comes in) of the electrician, is relied upon to design a circuit properly and ensure that the highest level of safety is applied to the installation as a whole