You'll want to make sure they're for F39T5/39W T5s.. looking on Menards website only lists F54T5/54W T5s (and one 28W,) which makes sense since 4ft bulbs going to be a lot more common for recessed ceiling lights etc. Same with home depot and lowes, the few T5 ballasts they have are usually 54W, at least that I've seen in stores locally and on their websites, so you'd likely be outta luck their as well for your setup.
Fullhams Workhorse line is T8/12 ballasts. Their Racehorse line is their T5 line.
I've seen ballasts before listed for running F39/F54 like what DFW lined above and assume they have some type of internal regulator for the two, honestly though I've never looked into it - it could just be a marketing thing. Even if the ballast is only designed & labeled for a 54W bulb, a 39W bulb certainly would work in it but likely going to overdrive the bulbs and inconsistently at that from bulb to bulb or exactly how much so color spectrum and bulb life are a toss up. Not sure if it would affect the ballast or not, again I haven't looked into it. If any of the current ballasts work a little testing could be interesting. If none of them are, that'd tell me something with that many failed ballasts.
+1 to infinity, can't find a better ballast IMO. The only one use for replacements. Very long lived and reasonable price. Have one that has been in use for 10 years, can't beat that
Life span and color shift. I tried the IceCap route on a previous setup which are well known for over-driving the bulbs and was lucky to get 9 months out of bulbs.
Ah yup they do list it for them. The ballast factor shows it's mostly under or over driving the lights though, and are also instant start. Under driving will likely get you longer bulb life, but again you're not going to get the advertised bulb color spectrum or the best par. Glancing at the specs theres a couple applications they do look ok though, and if you've had good luck with reliability and happy with the color spectrum and bulb life you're getting, all the more for ya.
