Let's start by saying I'm very ignorant on this topic, assume nothing special about the work invovled, so no need to get buried in the details. I simply need to know what the standard AIC rating should be for an MDP panel if i was to use four 15 ton RTUs.
Help is greatly appreciated.
There is no way to answer that question given the information you presented.
The AIC rating of the panelboard has to exceed the available short circuit current at the point where it connects to the electrical supply. It has nothing to do with the loads it serves at all.
The biggest issue you will likely encounter is the short circuit current rating of the RTU control panels. They often come in at 5 kA because that is the cheapest they can be made.
You need to get an engineer to look at your power system and figure out what the available short circuit will be at point where the panelboard gets its supply and specify a panelboard with an AIC rating in excess of that value.
The engineer would also need to look at the available short circuit current that will be available at the point of connection to the RTU control panel and you would need to specify RTU control panels with an SCCR that exceeds that value.
