T5/HO ballasts are application specific. The first technology where this was the case, and an ICN4s54 is not intended to run F39T5/HO lamps. It just burns them up. IceCap had some trouble with this, saying that their 660 T12/VHO ballast was suitable for running T5/HO lamps. I have an ICN-2S54 in my hand and the ballast says: FT36/39W, which is a CFL, not a T5/HO. You need to get your hands on a ICN-4S39 ballast, if you want to run 39watt T5/HO lamps. Easy enough mistake to make, but can get expensive blowing out lamps.