This is important to know because under-sizing wires and over-sizing breakers can lead to potential fire hazards.
50 Amp Electric Range
Old range ovens require a 50 amp breaker because of the massive load that the stoves use for baking. Six AWG size copper or aluminum wiring is acceptable for this size circuit. If aluminum wiring is used, it has to be installed into a CU/AL breaker. This means that the breaker accepts copper or aluminum wiring. The outlet that the stove is plugged into also has to accept aluminum wiring if it is used.
40 Amp Electrical Range
Most of the newer Energy Star rated electric ranges require a 40 amp breaker. Eight AWG wires are required from the breaker to the outlet the range is plugged into. If aluminum wiring is used, it has to be installed into a CU/AL breaker. The outlet that the stove is plugged into also has to accept aluminum wiring if it is used.
Grounding
All the circuits have to be grounded at the outlet and at the panel on the grounding bus bar. All grounding connections must be tight and the sheathing must be free of nicks or gashes.
Voltage
All circuits are required to be double pole 220 amp circuits. Failure to adhere to this rule can result in a potential fire hazard. Forty and 50 amp circuits are used for electric ranges depending on the age and electrical requirements.