Can I upgrade from a 240V 30A circuit to a 240V 50A circuit?
To increase the amp rating of your circuit breaker, you almost certainly need to increase the gauge of all the wiring on that circuit. Circuit breakers are there to protect the wiring for overloading, overheating, melting the insulation, and eventually starting a fire.

Typically, you have the following wire gauges (this may vary with long circuits and your local codes):


15 amps: 14 gauge
20 amps: 12 gauge
30 amps: 10 gauge
55 amps: 8 gauge
75 amps: 6 gauge


So going from 30 amps to 55 amps requires you to rewire that circuit from 10 gauge to 8 gauge wiring.

For your oven, check the specs on the oven itself. It may simply have a plug that's designed for multiple ovens and will work on a 30 amp circuit.