Re: AIC ratings
You must get the actual KAIC value from the power company. If it's at the service entrance that is where you start, i.e.' 10kaic is quite common for residences and, with the more robust residential distribution systems that are being install be the power companies may be up to 22kaic. Commercial and industrials can be 65-100kaic and possibly more.
But, be that as it may, you must know what the KAIC is at the service entrance first. If your distribution sytem is to be "fully rated" than all of the downstream devices must be rated the same as that of the service entrance.
Should a coordination study be done by a qualified person, the impedance of that distribution system is used to calculate the actual fault current available at a give point in that distribution system and , as such, a device with a lower kaic rating may be applied at that point. That would be a coordinated system as it wouldn't be required to be fully rated. This does save money because devices with lower kaic rating are often less expensive.
If that service entrance feeds a transformer, with the value of the kaic on the primary of the transformer known, the available fault current at the secondary is determined by the KVA of the transformer and its impedance with consideration to motor load contribution. Again, if a coordination study is not done, all of the components must be fully rated for the available fault current available of the secondary of the transformer.
However, in any even, fully rated or coordinated, one must be carefull as a future change in the service entrance or kva of a transformer may result in a change in the available fault current.