Electromagnetic transformer components include a magnetic core and at least two conductors assembled with the core and defining respective windings completing different numbers of turns. The conductors are fabricated from a composite material including carbon nanotubes having an improved conductivity. The transformer is fabricated to have performance parameters that are selected in view of a function of a ratio of conductivity and/or a function of a ratio of effective diameter of the composite conductor material relative to a reference conductor material as conventionally used in a transformer fabrication.