10 guage.
6ga should be used. It might not be against codes where you are,and you might have a 50amp installed for something that only uses 40amp, but it should be done right, and 6ga should be used off of a 50amp breaker.
30 amp breaker with #10 gauge copper wire
Use AWG # 6 wire.
20 amp breaker 12 gauge wire assuming its 120 volt
AWG 12.
AWG # 14 copper.
#10 cable is no good for 120 amps, you need #2 cable, and it can be used at a distance of 250 ft.
No, 10 gauge wire requires the use of a 30 amp breaker. A 20 amp breaker is only used on 12 gauge wire.
Yes. In the US at least.
A double pole 30 amp breaker can pass 30 amps per pole, therefore #10 wire should be used.
In residential wiring applications the most used is 14 gauge wire for light switches as long as the circuit breaker or the fuse is 15A. If your lighting circuit is on a 20A fuse/circuit breaker then you need to use 12 gauge wire
running wire 12-2 300ft w/9ea. 27watt lights what size breaker should be used