This is called up in the instructions for installing a digitally
controlled non-electric shower. The water controlling box runs off
12v dc from a separate psu connected to the mains.

The actual requirement of "a separate, permanent connected supply must
be taken from the consumer unit to the appliance", would suggest that
that this supply is to be a radial from it's own MCB. This is
nonsense surely and looks suspiciously like someone has just copied
the instruction set for a mains driven electric shower.

I've advised using an fcu from the nearby ring circuit, but is this
likely to run into problems with people like insurance companies as
the manufacturer's instructions have been ignored ?

Rob

robgraham wrote:
[...]

The actual requirement of "a separate, permanent connected supply must
be taken from the consumer unit to the appliance", would suggest that
that this supply is to be a radial from it's own MCB. This is
nonsense surely and looks suspiciously like someone has just copied
the instruction set for a mains driven electric shower.

It does look that way, from what you've said. It may be though that all
they're trying to say is it must be hard-wired (to an FCU on a suitable
circuit) and not connected using a plug'n'socket.

I've advised using an fcu from the nearby ring circuit, but is this
likely to run into problems with people like insurance companies as
the manufacturer's instructions have been ignored ?

Try contacting the manufacturer or importer to obtain clarification
an/or make a complaint. You're quite right though - BS 7671 now
requires manufacturer's instructions to be followed, which is a problem
when so many instructions are utter crap, or the authors simply have no
knowledge of UK wiring practice.

--
Andy