A #8 copper wire with an insulation factor of 75 or 90 degrees C is rated at 45 amps.
That would depend upon how many amps will be used in the sub-panel. For example, a 30-A subpanel would need a minimum of 10 AWG feeder conductors.
140 AMPS
3/0 gauge
Yes, # 4 AWG copper and 100 amps is the max.
Typically 30 amps.
50 amps
The amps that a four gauge wire will handle will depend with the thickness of the wire. If the wire is thin, the four gauge will handle 95 amps.
That would depend upon how many amps will be used in the sub-panel. For example, a 30-A subpanel would need a minimum of 10 AWG feeder conductors.
140 AMPS
15 amps
The recommended wire gauge for carrying 80 amps of current is typically 6 AWG (American Wire Gauge).
An 18 gauge wire can typically handle around 16 amps of electrical current.
An 18 gauge wire can typically handle around 16 amps of electrical current.
A 14 gauge wire can typically handle up to 15 amps of electrical current.
The maximum amperage capacity of the 400 amps main panel in this electrical system is 400 amps.
3/0 gauge
50 amps