A.Lee wrote:

How many lights are required (12v 20w iirc) to illuminate a ~6 feet
square bathroom?

Four should do it. Go for the wall washing effect to get more
omnidirectional lighting.

I was thinking 4, plus an extra combined fan/light over the bath.
Are there any kits with the PIR included?

Not usually - but you can buy standalone PIR easily enough.

PIR sensors. Easy to fit? Reliable?

yup

How do they work? say it is daytime, but you want the lights on, will
they turn on then?

They usually let you control their dusk detection to the extent of being
off, so they will run all the time.

One thing you may need to lookout for is if you are soaking in the bath
and the lack of movement allows all the lights to go out. You might have
to wave a hand from time to time! (I think I would be tempted to fit a
switch in parallel so that you can force them on when you need)

--
Cheers,

John.

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