Jim, thanks for the reply. I don't know why he just used 12 AWG. I thought maybe due to the short distance, and the air compressor being just a 2hp small unit.
I have been using this outlet, with the 50' 12 ga extension, thinking this is giving more amps than the outlet on the front of my garage, that is only on a 15 amp breaker, and 14 AWG wiring.
I may eventually do the 30 amp 10 AWG, just for my RV, but just not going to get it done this year. I am somewhat overwhelmed with other priorities, that just never seem to let up.
Jerry