[shalu]

I would like to add one more comment on ballast factor. Based on my measurements above and going through ballast specifications, I realized one general fact about ballast factor for multiple bulbs: the ballast factor drops as more bulbs are connected, meaning each bulb will get less power/light. Take the Advance 4x ballast I used. When all four bulbs are connected to the ballast normally, the ballast factor is 0.88, about 28w each. When one bulb is connected(other leads from the ballast are free), I was getting 40w, or BF=1.25. Connecting 2 or 3 bulbs result in something in between(at 3 bulbs, BF=1.0 according to ballast spec).