Many good sources:
IEEE Red Book- highly recommended. (ANSI Standard 141- "Recommended Practice for Electrical Power Distribution for Industrial Plants").
Eaton's (Cutler-Hammer/Westinghouse) Consulting Applications Guide- the engineering section has good summaries of the technical details and good information on equipment. It might be on line or request a CD or printed version form your local rep.
Siemens Specification Guide - similar to the Eaton book.
Look at manufacturer's web sites and read every technical white paper you can find. Powell Electric Manufacturing?s web site is a great place to start.
Okonite cable's website for MV cable design. Other suppliers have similar information: Prysmian, General Cable, Southwire.
GE Industrial website used to have several good application articles on short circuit calculations and equipment design.