The grounding behaviour is a critical aspect in a windmill lightning protection system because can appear sparks due to a higher surge and damage parts of the windmill [1][2]. This paper proposes a model to a lightning current path across the windmill up to earth including non linear components of the grounding system. Moreover, different lightning current waveforms are employed in the simulations as well as the effect of first return stroke and subsequent return strokes [3]. This performance allow study the effects of the subsequent return strokes that normally have less current amplitude but faster rise times than the first return stroke.