15 amps.
For a 15 amp circuit, a 14-gauge wire should be used.
The appropriate gauge size for a 10 amp wire in a residential electrical circuit is typically 14 AWG (American Wire Gauge).
A #14 wire will do fine for grounding a 20 amp device. That is the size of the ground wire in a 2 conductor # 12 wire building cable.
The size breaker you use is determined by the size wire used in the circuit. If you use AWG #12/2 wire then use a 20 amp breaker. If you use AWG # 14/2 then use a 15 amp breaker.
The correct size fuse needed is based on the size wire used in the circuit. The size wire needed is based on the load that will be applied to the circuit. 1. AWG 14/2 wire = 15 amp fuse 2. AWG 12/2 wire = 20 amp fuse 3. AWG 10/2 wire = 30 amp fuse 4. AWG 8/2 wire = 40 amp fuse
The purpose of a fuse it to protect the wire that goes to the load. A 15 amp fuse protects a #14 gauge wire. A 20 amp fuse protects a #12 gauge wire. To answer your question if the wire size is #12 coming from the 15 amp fuse now then it can be upped to 20 amp fuse. If it isn't then you are taking the risk of overloading the #14 wire with a 20 amp fuse. This can lead to insulation failure of the #14 wire, overheating with the possible outcome of a fire breaking out somewhere in the circuit.
The appropriate wire size for a 20 amp circuit is typically 12-gauge wire.
The appropriate wire size for a 25 amp breaker is typically 10 gauge wire.
For a 25 amp circuit, the appropriate wire size is typically 10 gauge wire.
The appropriate wire size for a 30 amp breaker is typically 10 gauge wire.
The appropriate wire size for a 30 amp circuit is typically 10 gauge wire.
The appropriate wire size for a 50 amp circuit is typically 6-gauge wire.