The influence of the number and position of air gaps on the 50% AC withstand voltage, V50, of a short string of 5 IEEE standard insulator units covered with ice was experimentally investigated and numerically simulated. The results show that the V50 is affected by the number and position of the air gaps. The results also show that the presence of a partial arc along the air gap close to the high voltage (HV) electrode leads to a redistribution of the voltage along the ice-covered insulator. Based on the obtained results, suggestions for improving the performance of line insulators under icing conditions were proposed