Winged Cat wrote:
Hi
I am going to fit four LV IP44 halogen spotlights in my bathroom
ceiling. The room is 190 * 175, and I am trying to decide on the best
positioning of the lights. I don't know whether to arrange the lights
equidistant from the centre of the ceiling, or equidistant from the
edges, IYSWIM.

"Normal" is "anything that works". The unquestionably best way of
finding what works is to tack the lights up temporarily - hold in place
with a single screw, say - and see what lighting pattern results.
Halogen spots give rather sharp shadows, with high resulting contrast
between the illuminated areas and the shadows. Experiment with
positioning until you're happyish - and also try some electrical
counters or on-line suppliers for wider-angle reflector bulbs (unless
your IP44 fittings use a capsule bulb and have their own reflector,
natch) - though sheds tend to sell only "spotlight" bulbs which
concentrate most of the light into a 20-degree-or-so beam, the mfrs also
make wider-angle blubs which roughly double that angle (38 degrees is
the nominal figure in my head), which can help to give more of a wash of
light than a number of illuminated pools.

You might also end up deciding to complement your spots with a
"background" tungsten source - maybe over the mirror above the sink, say?

HTH - Stefek