Many moons ago, I recall an extractor which had rechargeable batteries in a
little well quite big box which also had a mains to low voltage psu in it..
The idea was that the batteries kept the fan on for a few minutes after the
mains went off. I remember at the time thinking, this looks like a bit of a
problem when the batteries start to not hold a charge!

Brian

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"John Rumm" wrote in message
o.uk...
On 27/10/2020 14:57, me wrote:

I'd like to wire the shower room extractor fan from the shower
pull-switch so that it goes on with the shower and not the light. I
found some info where one person said it's a no-no under current
wiring regs but could be done via a contactor, and another says it
can be done without a contactor as long as it goes via a fused spur
from the shower switch.

Any electricians here can tell me which is the legal way to do it as
I'd like to do it through a fused spur from the shower pull switch
for simplicity..

You can do it with a fused spur from the shower isolator switch it you
want. You should label it at the consumer unit to avoid surprises for
later maintainers. Also since you would be removing all power from the fan
when you turn the switch off, you would lose any ability to have a an
automatically timed run on after the shower.

If you wanted to power and trigger the fan from the lighting circuit, but
also trigger it from the shower circuit, then you get into the realms of
needing contactors/relays etc to keep the circuits electrically isolated
from each other.


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Cheers,

John.

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