Personally, I would just buy a plug-in shaver adaptor from a hardware store and call it "job done".

But...

1. Yes.

2. Why? The MCB should be specified to protect the cable, not what's connected to it.

3. Only if the manufacturer's instructions call for a fused supply.

What do you intend to plug into the new shaver socket, and is it in a location that would require a socket with an isolating transformer? Basically shaver sockets near sinks need one, those in bedrooms an similarly dry places do not.

However, the non-transformer kind while better for long duration loads like rechargeable toothbrushes etc (many designd are really best for intermittent loads like a shaver and can overheat a bit with a long duration load.) really ought to be on an rcd protected supply - you do not mention if the old water heater supply has an rcd or not, but in any wiring more than a few years old, it may well not..

With those caveats, yes you certainly can.
Mike

in a cupboard that used to hold an immersion heater,

Is there still any hot plumbing in the cupboard? Airing cupboards were notorious for causing problems with 13A sockets (and FCUs) feeding immersion heaters - the ambient temperature is often far too high for BS 1363 accessories and they'd often overheat as a result - I'd be concerned that a transformer type shaver socket could suffer similarly.

   - Andy.

" and is it in a location that would require a socket with an isolating transformer? Basically shaver sockets near sinks need one,"

Isn't that only if the socket is in zone 2? 

That is: near a bath or shower; not a basin.

strictly, yes, but if I was putting one in for myself, as the OP is, then the that makes hand held electricity and bare skin a greater hazard is water, and it comes the same out of taps of all kinds.

But strictly to the regs you are correct of course.

Mike

Blokes could of course grow a beard and stop wasting time. Then, for some odd reason, an image comes to mind of girls shaving their legs in the shower with an electric razor.

It must have happened! :-)

however this is not perhaps the right part of the internet for those sort of images.... I understand that battery operated 'wet and dry' shavers exist for that task. They still need a 2 pin socket, either UK or Europlug style to charge though.

Mike

Hey Leo!

It's possible to install a shaver socket in the cupboard where your immersion heater used to be, using the existing wiring. Since the dedicated supply from the consumer unit is rated at 16 amps, you'll need to replace the MCB with one at a lower rating, say 3A, to ensure that the shaver socket is protected from overloading.

It's also recommended that you install a 3A FCU (Fused Connection Unit) to protect the shaver socket from any electrical faults. This FCU will have a fuse that will blow if there's a fault, protecting the shaver socket and any electrical equipment plugged into it.

So, to summarize, you'll need to replace the MCB with a lower-rated one and install a 3A FCU to protect the shaver socket. This should be a fairly straightforward job for a qualified electrician.

Hope this helps!

That is debatable but, in any case, why would you need to do both?

Many thanks for the helpful advice. I realise my initial request said "adjacent to the bathroom", but should have said "adjacent to the bath". The spell checker being helpful, perhaps? 

So, the cupboard is in the bathroom. There are some pipes in there, including a hot pipe for the show so yes, it does get a bit warm. I was wanting to use it mainly for safely charging an electric toothbrush, rather than using it for an electric shaver. 

Sorry for the confusion, any further advice much appreciated!