OK, think about this.
Ice Cap ballasts can run up to a certain amount of bulbs (depending on model) for a certain amount of linear feet, and a certain amount of wattage.
These same ballasts can run up to the same amount of wattage in PC bulbs, but are not measured in linear feet.
These are the maximums for these ballast.
They can however, run the same linear footage of NO bulbs, which have an extremely lower wattage. So in other words....The wattage maximum is just that (with an electronic ballast) a maximum. Meaning that you can run any combination of wattages, as long as you don't go over the maximum recommended wattage or linear footage (in linear bulbs)....
Does that make sense?