I'm going to install an outlet for a friend in his backyard and he is going to run a 15amp pump for his koi pond. My question is can I use 12AWG wire for the 130' run from the panel off an unused 20 amp circuit? Also he may use the new outdoor outlet for other things like a 300 watt low voltage lighting transformer. If you do recommend a 10 AWG wire what size circuit breaker should be used. Thanks.