The owner of Hydro Gardens{Tomatoes are his specialty}once told me that a tomato plant needs at least 1000 candlelight.
My T5 florescent lamp with 8 tubes gives off about 300 candlelight's about 10 inches away, And that rapidly diminishes the further you move away.Even with reflected walls.
The first time I grew tomatoes i used 400 W.
hps and that did pretty well. Then I decided to go to 1000 W
I think I've read that you need 40watts of light per square foot would be okay but 50 or 60 would be better.