On Sun, 13 Apr 2008 08:46:11 +0100, (A.Lee) wrote:

I have seen one bathroom where there is a PIR sensor inside the door,
which lights up around 6 ceiling mounted low voltage
spotlights/downlights. I'd like to replicate this.

You don't want to - really. At 03:00 hours when someone wanders into
the bog, their way lit only by the gentle reflection of the sodium
lights on the council tip nearby, they are suddenly illuminated by
what, to dark adapted vision, is the equivalent of a small nuclear
explosion. Screaming gently they cover their eyes with their hands
and blunder into the throne cracking their shins. This causes them to
rebound back into the cupboard spilling its contents on the floor.
Lacerating their feet on the broken glass, and all thought of a period
of gentle contemplation long past being necessary they stumble out of
the room whereupon the lights go out and in what is now to them total
darkness they fall down the stairs breaking both legs and injuring the
cat.

Someone I know fitted a similar system and when they got out of
hospital attacked the PIR with a hammer and for overnight use mounted
one small red LED in the centre of the ceiling. It comes on at about
23:00 and provides enough illumination for midnight forays to the loo
without dazzling anyone.

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

Depends on the type of light. Downlighters (preferably a small
galaxies worth) are much favoured by those who like the "footballers
girlfriend" style of decor and they go well with gilt taps, fluffy
dice and looy the quinze mirror embellishments. The most common
mistake is to put them above mirrors where they cast strong shadows on
the face. Moreover, with downlighters when lying in the bath your
retina is burned out by the hideous bright point sources scattered
around the ceiling. They are cheap however.

Ideally you should have several lighting types capable of being
switched as you wish. For night time excursions a very low power
light connected to a PIR can be useful. It need only be a few watts
and need not be in the ceiling (LED lamps are useful here). Its
purpose is to provide sufficient light for someone who is already dark
adapted to do what they must and stagger back to bed still half
comatose.

For morning ablutions and face painting then theatrical lighting - two
vertical lights either side of the mirror - is best and should be
coupled with high ambient light levels.

For sitting in the bath with a book and bottle of wine dimmer lighting
and a lamp behind the head somewhere (it can be in the ceiling but
well back from the head) to illuminate the book are ideal.

http://www.thisoldhouse.com/toh/arti...403815,00.html

http://www.barefootfloor.com/light-y8.html

might give you a few ideas.