down lights

Because a) I'm making a "modern" style house and I want things clear for
little hands, I'd like to use 12V 3mm 50mah wheat grain lights mounted into
the ceiling for most of my rooms. Is this ok or a fire hazard or just not
done for some reason?

I'm going to drill and mount one bulb and run it for several hours tonight
as a test but maybe someone's got a better idea? Super bright led's? I know
they put out a lot of light?

Obviously I'm trying to make as many fittings as I can.

My power supply is 0-12V 5amp variable with current limiting. ie 60 watts so
power supply shouldn't be a problem. I'd just hate to turn on the lights and
have the house burn down followed by the house burning down. Cheers
Glen