Let's say I have a device that calls for 30 ampere overcurrent protection. In the main panel I install a double pole 30 AMP breaker, and use it to feed a subpanel near the device. The device also requires GFCI protection, but all I have is a 50 AMP double pole GFCI breaker. Can I install the 50 AMP GFCI breaker in the sub panel, and feed the device from it? If so, how do I size the conductors from the 50 AMP breaker to the device? Should the conductors be sized at 30 or 50 amps?