Which size of fuse or circuit breaker would be appropriate to use with a circuit that uses AWG number 14 wiring?
Why A fuse or breaker protects the wire, not the equipment, so it must open before the conductor can overheat. Under the National Electrical Code, AWG 14 copper branch-circuit wire is limited to 15 amperes, so a 15 A breaker or fuse is the largest allowed. Using anything bigger lets the wire carry more current than its insulation and ampacity rating allow, creating a fire hazard.
Watch out The 20 ampere choice is the correct rating for the next larger wire, AWG 12, not for AWG 14; oversizing the breaker means the wire fails before the protection trips.
14-15, 12-20, 10-30: smaller gauge number, bigger wire, bigger breaker.