I've finally constructed a nice lightbox after using simple UV bulbs in suspended reflectors for some time. I went from a bank of 4 - 20w tubes to an array of 10 tubes. I used the original 2 ballasts I had been using and added to them 3 more identical ballasts for the extra 6 bulbs. Before, I was able to fire them up and they all started pretty much simultaneously. Now in the new box, they seem to fire randomly and it sometimes takes 20 - 30 seconds for all to fire. I do not seem to be able to get them to all fire at once and cannot feel confident enough to simply slide in my frame and turn on the timer. I have to fire it up, make sure they are all firing, cajole the ones that do not by touching the bulb... something I do not want to continuously do due to exposure to the UV.

Anyone have suggestions or similar problems?

I have gone basically from Jon Edwards' design as well as other similar ones I have found online. All bulbs are new and this seems to happen randomly. I have checked and rechecked the wiring, sockets, etc. If I could repeat this every time it would be easier to diagnose. I thought it might be a short due to having to touch the bulb to get some to fire, but as I said, it is random. Also, all it takes is a very light touch to make a bulb fire. It seems more the touch than the actually jiggling of a short.

Any help or suggestions appreciated. I am baffled.