The data plate of this fairly new Exterior Trane A/C unit shows a minimum circuit ampacity of 17 Amps and is provided with a 12 AWG Cu (rated for 20 Amp) conductor connected to a 30 Amp breaker (unit disconnect also has 30 amp fuses).
I figure that this is so the breaker doesn’t trip at start up each time. But the question I have is**…should the conductor be a 10 AWG Cu (for 30 amps) or is the 12 AWG CU considered okay since the start up surge is so short and unlikely to damage the 12 AWG Cu or create a fire hazard.**
My feeling is that the conductor is too small…but wanted to check it out before submitting my report (later tonight)