Ok, so my "shop" is really just my garage. It's about 20' x 26'. I currently have 4 standard single bulb fixtures in the ceiling, arranged in a square, distributed fairly evenly across the ceiling. I'd like to upgrade my lighting. I wouldn't trust myself to do much electrical work, but I think I can manage swapping out these fixtures for fluorescent strip lights. I don't want to rewire anything in the garage. I want to place the new lights in the same place as the old lights. My question is, how many lights would I want? Most fixtures come in 1, 2, or 4 bulb fixtures. And most that I've seen use 4 foot long bulbs.
Assuming I'm only using 4-foot T8 fluroescent bulbs, how many bulbs would provide adequate lighting in a garage 20' x 26' (9 foot ceiling)?