On Sun, 30 Aug 2009 16:12:58 -0700 (PDT), sid
wrote:

Finishing my basement and I need to calculate the number of can lights
needed to install in the drop ceiling. Dimensions are approx 21' x
22' and 7'7" high. I read one post recommending a can light every
4' and another every 6'. I want the space to be lit enough for work
space or food prep, but most of the time I intend to dim them down to
reading, PC, or TV watching levels.

Any suggestions on how to calculate the number and placement of cans ?

Thanks

Lighting design is a bit more involved than that. You really should be
thinking about dedicated task lighting exactly where you will be doing
tasks, and other lights for ambient illumination. These two uses
require different types of lighting. You may even want to consider
splitting up the ambient light so that you can acheive "dim" by only
turning on some, rather than all of the lights. That will save a lot
of electricity over using dimmers, and even allow you to use CFL's,
which will REALLY save electricity.