Funzbo wrote:

The builders who installed it (before my time here) put the (non
switched) Fused Unit in the (stud) wall above the bath (ca. 50 cm from
the shower head).

Ohhh nice...

I would like to move the fused unit to outside the bathroom, as
recommended in the regs (required?) and replace it with a switched fuse
unit.

You can have the FCU in the bathroom if you want, preferably in zone 3
though. In addition to the FCU you will need a THREE pole isolator
(hence a FSU is not going to help you in this case)

I want to be able to override the fan using the switch, but still be
able to use the lights.

All the diagrams I have seen for overrun fan wiring show the FSU in the
supply BEFORE the light and fan.

That is fair enough... however the isolator should be between the fan
and all sources of power including the switched live.

It doesn't seem logical to have a double-pole FSU going to the fan if
there's a switched live that may still be live even though the FSU is
open circuit.

Its not... there are three requirements for switching and fusing.
Functional switching, which is provided by the light switch and the
timer in the fan. Isolation, which will need to be provided by a purpose
made three pole isolator (these are available in conventional single
pattress switch form and also as a ceiling mount pull switch), and
fusing, which will need to be provided in the main power connection to
the lighting circuit.

How should I wire it to get what I want.

Personally I would place the three pole isolator in the circuit first,
with a plain FCU (i.e. non switched) FCU after it close to the fan
position. That way you can isolate the FCU as well as the fan should you
need to change the fuse.

Part-P question: since I'm moving wiring OUT of the bathroom I'm
presumably in the clear?

Probably not, since you will need to alter wiring in the bathroom to
effect the change... your call ;-)


--
Cheers,

John.

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