What is the right Wire size for 50 amp circuit?

Answer for USA, Canada and countries running a 60 Hz supply service.

A #6 copper conductor with an insulation factor of 75 or 90 degrees C is rated at 65 amps.

Before you do any work yourself,

on electrical circuits, equipment or appliances,

always use a test meter to ensure the circuit is, in fact, de-energized.

IF YOU ARE NOT ALREADY SURE YOU CAN DO THIS JOB

SAFELY AND COMPETENTLY

REFER THIS WORK TO QUALIFIED PROFESSIONALS.