Electrc 2005 NEC Calculator Trial Versio
Electrc 2005 is designed for electrical contractors, engineers, inspectors, estimators, and electrical maintenance personnel. It performs wire sizing, conduit fill, motor, lighting, panel schedule, transformer, voltage drop, box fill, fault current, and power factor correction calculations. ... Many NEC parameters are supported, including parallel conductors per phase, ambient temperature derating, terminal temperature derating, quantity of current carrying conductors derating, circuit type, voltage drop percentage, and more.
http://electrc.net/E05TrialDirectory/Elec5T11.exe - 5Mb - Download - Screenshot

Electrist
For figuring everything electrical nothing else even comes close. Try the free trial of Electrist and see why electronic engineers in some of the finest R&D laboratories in the world, industrial maintenance crews, power utilities, RF & audio engineers, circuit designers, telecom engineers, and... You can also enter any conductor properties and accurately find the voltage drop. ... Size 3 phase panels & transformers with the built in load calculator. ... Enter any number & configuration of delta or wye/star and 3 phase, line-to-line, line-to-neutral, and/or centertap-to-neutral to instantly...
http://www.RedBinary.com/files/electrist/132/Electrist.zip - 96Kb - Download - Screenshot

RF ToolBox
RF Toolbox is an antenna design and electronics/electrical tool package. It takes you step by step through the design of the following types of antennas: Dipole Fat Dipole Yagi J-Pole Super J-Pole Log Periodic Cubic Quad Vertical helical It also performs the following calculations: Transmission... The load impedance can also be calculated from the measured impedance at the line input. ... With the transmission line calculator, you can select the type of line, length, operating frequency, and calculate the losses, as well as the SWR and losses from SWR due to impedance mismatch.
http://www.blackcatsystems.com/download/RFToolbox.zip - 400Kb - Download - Screenshot