For a 125 amp circuit using THHN wire, the appropriate wire size would be 1/0 AWG.
The recommended wire size for a 100 amp circuit using THHN wire is typically 3 AWG (American Wire Gauge).
The appropriate wire size for a 20 amp circuit is typically 12-gauge wire.
For a 25 amp circuit, the appropriate wire size 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.
The appropriate wire size for a 60 amp circuit is typically 6-gauge wire.
The appropriate wire size for a 20 amp 220v circuit is typically 12-gauge wire.
The appropriate wire size for a 220v 30 amp circuit is typically 10 gauge wire.
The appropriate wire size for a 240V 30 amp circuit is typically 10 gauge wire.
The appropriate wire size for a circuit requiring 60 amps is typically 6-gauge wire.
The appropriate wire size for a 240V 50 amp circuit is typically 6 AWG copper wire.
The appropriate wire size for a 50 amp 240v circuit is typically 6 AWG copper wire.