IEC standards define creapage distance depending on the Class of insulating materials ( based on the CTI) . Multiplicator factors are defined to take into account the effect of altitude. ( up to 5000m).

Other test are used to determine the effect of contaminant ( ie : inclined-plan test)

At higher altitude, with surface polluted ( deicing fluids, hydraulic fluids, kerosene) , what tests we should use to perform characterization of polluted surfaces ? what would be the effect of altitude ? ( partial discharge, corona ?) , is it possible to determine creapage distance ?