46 CFR §111.51-2

1. (a)The available short-circuit current must be computed—
   1. (1)From the aggregate contribution of all generators that can simultaneously operate in parallel;
   2. (2)From the largest probable motor load; and
   3. (3)With a three-phase fault on the load terminals of the protective device.
2. (b)The calculated currents must be used to select suitably rated equipment and to allow the selection and setting of protective devices.