15.) The lack of verification of the available short circuit current at the supply terminals of service equipment.
This situation is more common in large commercial and industrial installations than in dwelling unit installations. Section 110-9 requires that have an interrupting rating sufficient for the current that is available its supply terminals. The available short circuit current is also described as available inrush of current or AIC rating. In short, the service equipment must be able to withstand the available fault current supplied by the utility company transformer(s). The local power company can give you the available fault current at the secondary terminals of their transformer. However, the service equipment is only required to withstand the fault current at it's supply terminals. Depending on the size and length of the overhead or lateral conductors the available fault current could be considerably less at the service equipment terminals than it is at the transformer terminals. There are formulas available for computing available fault currents.
Example: if the available fault current at the terminals of the service equipment was 30,000 amperes and the equipment only had a 10,000 or 22,000 AIC rating and a fault occurred it is likely the equipment would be significantly damaged trying to clear the fault. In many cases there are injuries to personnel as well as damaged equipment as a result of under-rated equipment. It is the responsibility of the Master electrician to verify that the equipment is sized for the available fault current.