The CYMCAP software is dedicated to performing ampacity and temperature rise calculations for power cable installations. Determining the maximum current power cables can sustain without deterioration of any of their electrical properties is important for the design of electrical installations. It addresses steady-state and transient thermal cable rating as per the analytical techniques described by Neher-McGrath and the International Standards IEC 287© and IEC 853©. This software was developed jointly by Ontario Hydro (Hydro One), McMaster University and CYME International, under the auspices of the Canadian Electricity Association. The validation of the results obtained with the CYMCAP software provides increased confidence when upgrading existing power cable installations and designing new ones, thus maximizing the benefits from the considerable capital investment associated with them.