The strong correlation between the level of eddy current losses and the winding geometry shows the necessity to pay attention to the manner of disposition of coils in machine slots. The conductor type whether it is solid or stranded has also a crucial influence. This article suggests an electromagnetic analysis of complex stranded conductors such as Litz and twisted wires. Each conductor is decomposed into individual strands that are woven or twisted in the slot throughout the machine length. Combined with several electric circuit relationships that interpret the strands transposition, a 2D finite element model is developed in this article so that the copper losses in each strand can be calculated individually. A model reduction is also proposed in case of Litz wires. It allows benefiting from only one complete finite element solution to find fast solutions in the slots’ domains when any variation of geometrical data occurred. It allows adapting non conforming subdomains’ meshes and seeing that it prevents the Newton-Raphson iterations and the moving band technique, the model reduction presents clear interests in repetitive analysis such as winding optimization processes.