This paper compares different squirrel cage designs under starting and running performance. Inrush current, torque, stall time, maximum number of consecutive starts, efficiency, power factor, critical speed and cage stress are discussed along the paper while considering aluminum and a copper alloy cages. For the sake of comparison two machines were selected to perform the study -one 4-pole 6500 HP and one 18-pole 3500 HP. In addition, procedures of repairing fabricated copper and aluminum cages are discussed.