No kidding... this guy is a nincompoop. I don't know of any 480V rated breaker that will not have a 240V AIC rating as well. For 208V they sometimes do say to increase it by 10% ,althoughg most just say to use the 240V rating, it's usually plenty high enough.
What you might find is breakers that have a rating at 240V
but not at 480V, because the breakers themselves are not rated for 480V, so having an IC rating at that voltage is a moot point. But it never works the other way, if a breaker is rated for 480V (or more likely 600V), it is rated for anything below that, and the UL listing will specify the kAIC rating at all possible nominal voltages.
Interrupting capacity is based on the energy in the fault, so as the voltage goes down, the IC rating of the breaker goes up. For example I'm looking at some C-H breakers that are rated 35kAIC at 480V, and 85kAIC at 240V, I seriously doubt that GE makes their breakers any differently where that is concerned. So it's possible to interpret his missive as "not untrue", but he was being a lazy ass. All he would have to do is open a freaking catalog.
