GenCalc 1.0.0007 could be downloaded from the developer's website when we last checked. We cannot confirm if there is a free download of this software available. This free software was originally developed by BICCGeneral NZ Ltd. We recommend checking the downloaded files with any free antivirus. The software lies within Education Tools, more precisely Science Tools.
From the developer:
GenCALC helps electricians and designers ensure they select the most appropriate cable to safely carry the required load and comply with the Wiring rules. By specifying the load, route length, installation conditions, cable type and allowable volt drop, GenCALC gives a list of cables that comply, sorted by conductor size. Other menus check limits on existing circuits.
You may want to check out more software, such as GASEQ, NI-DAQ or Family Tree Legends, which might be similar to GenCalc.