The switch must be within sight of the shower or of the type that is
lockable-off for maintenance.
A friend of mine has an electric shower, but the isolator is a switch
outside the room above the light switch for the bathroom - as this switch
can't "see" the shower (It is on the other side of the wall to the shower
unit), should this be a lockable one then?


It should be, so that there is no risk of someone switching on when
someone else is working on the shower.


Has there always been this requirement, as this was installed, maybe, 10
years ago.


16th Ed regulations were in force 10 years ago, so yes.


This is in reply to Owain's message 12/13 but I get a fault message
when I try to respond directly to either message.

I have just re-read BS 7671 (latest Brown cover edition) and cannot
find any reference to such a requirement, only to a general requirement
to reduce the risk of inadvertant re-connection of an isolator
(Sections 461, 462 and 537). Maybe I have missed it - can you quote
the reference please?

Incidentally, I have also checked back on the installation instructions
for a Wickes shower and a B&Q shower that I installed 5 years and 7
years ago and there was no mention in these instructions of such a
requirement either.

CRB