I would use AWG # 4 copper.
AWG # 10 wire on 30 amp circuit.
The ground wire in a two or three conductor #12 cable is a #14 bare ground wire.
The size of the wire is set by the maximum current it has to carry. The voltage sets the size of the insulation. In the UK a 230 v (nominal) ring-circuit supplying a set of power sockets is rated at 30 amps and uses a ring of 2.5 sq-mm cable.
For a 70 amp service at 240 volts, you would typically use a wire size of 4 AWG copper wire. This wire size is suitable for carrying 70 amps of current safely over a 240 volt circuit. Be sure to consult local electrical codes and regulations to ensure compliance with requirements in your area.
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 recommended wire size for a 220 volt circuit according to the 220 volt wire size chart is typically 10 gauge wire for a circuit with a maximum of 30 amps.
AWG # 10 wire on 30 amp circuit.
The recommended wire size for a 220-volt electrical circuit is typically 10-gauge wire.
The wire size depends on how much current it will conduct.
The recommended wire size for a 30 amp 220 volt circuit is typically 10 gauge wire.
The appropriate wire size for a 220 volt 30 amp circuit is typically 10 gauge wire.
For a 220 volt circuit with a 30 amp capacity, the appropriate wire size would be 10 gauge wire.
For a 30 amp 240 volt circuit, a wire size of 10 AWG should be used.
For a 240 volt 40 amp circuit, the appropriate wire size is typically 8 AWG (American Wire Gauge) for copper conductors.
For a 220 volt circuit with a 40 amp load, the appropriate wire size would be 8 AWG (American Wire Gauge) copper wire.
For a 40 amp 240 volt circuit, a wire size of at least 8 AWG (American Wire Gauge) should be used to ensure safety and proper functioning of the circuit.
Use 8 gauge wire.