How to Calculate the Short Circuit Current rating Capacity for Cables??

Just recently i learnt something new..the basic concept of engineering..once again almost forgotten until I was asked this question..."Do you know how to calculate short circuit current rating capacity for cables?", for a moment i stop and think.. i didnt know what is the answer...
*(^-^)* - (embarrased)

From there, i didn't stop but I started checking through my text books, surf internets, discuss with my collegues who in charge with planning, protection schemes and etc..

I finally found the answer..it is just a very simple formula..

Isc = VLN/Sqr. Z^2 ; VLN = Line to Neutral Voltage
Z = Positive sequence impedance of the cable (u can get from the
technical particular of the cable)

Very simple right...wait a minute, don't be mistaken with the other formula where u need to add in the impedance of the transformerr and generators. U need this data when u want to know what would be the the short circuit current when fault occurs on any part of the system..