And then to add to the confusion, more conflicting info from their manuals (unless my 430 ballast is so old it doesn't get wired the same as other 430's-the label on the ballast says it'll only run (4)-2' bulbs, or (3) of any other size bulb)....
This is from the 35MB product brochure I linked (not just the 430 info).
430 Fluorescent Lamp Electronic Ballast
Along with the 660 model, IceCap fluorescent lamp ballasts have been the industry leader for nearly twenty years. Rugged, reliable, and
efficient are just some of the many accolades for this category classic ballast. The 430’s Versa-Lamp technology can drive all T5, VHO or
PC lamps in any combination up to 4 lamps, with a total not exceeding 330 Watts. It is fully dimmable when driving VHO lamps, operates
silently, and is fully repairable with a 3-year warranty. It is a high frequency solution for aquarium, industrial, UV, germicidal, and horticultural
applications. Available in 110V or 220V options.
660 Fluorescent Lamp Electronic Ballast
Along with the 430 model, IceCap fluorescent lamp ballasts have been the industry leader for nearly twenty years. Rugged, reliable, and
efficient are just some of the many accolades for this category classic ballast. The 660’s Versa-Lamp technology can drive all T5, VHO or
PC lamps in any combination up to 4 lamps, with a total not exceeding 440 Watts. It is fully dimmable when driving VHO lamps, operates
silently, and is fully repairable with a 3-year warranty. It is a high frequency solution for aquarium, industrial, UV, germicidal, and horticultural
applications. Available in 120V or 220V options
Must be voodoo involved that I just haven't figured out. Maybe the release of the ballast you have makes a difference? If so, it'd be nice to find that info somewhere, too...