Two airs on 30 amp

holstein13 wrote:

Furthermore, a 30 amp outlet can put out 30 amps for short periods of time. Each of your A/Cs can run for a short while on 15 amps so 2 times 15 makes sense.

The bad news is that 30 amp breakers are only designed for 80% draw continuous, over one hour so you effectively only have 24 amps to work with on a continuous basis.

I predict that if you continue to run both A/Cs, you will trip the breaker in a couple of hours. If you don't trip the breaker, something is probably wrong with the campground breaker and should be checked out.

On edit: I see that the high in Santa Barbara was only 81 yesterday. Were you in the shade? My guess is that both compressors were not working together for long periods. Try this again when the temperature is in the 90s and you probably won't have the same result.

Unfortunately you are confusing "design" and "the 80% Rule" adopted by the NEC in 1996. A CB is not as you believe "designed" only to operate continuously at 80%, but is designed to operated continuously at 100% under the testing conditions of it being in free air with an ambient temp of less than 104deg F. Because heat affects the number that a CB will actually trip at it is not able to accurately predict the continuous amps number it will trip when say in an enclosure so they are typically sized with the 80% rule as to the expected continuous load. Furthermore a "continuous" load is one that can expected to be drawn "uninterrupted" for a sustained period of 3 hours or more like general office lighting, and A/C operations are definitely not "continuous" if the load number includes the compressor since that cycles on an off. I could easily envision one sustaining 30A say in a pedestal when the ambient air temp is only 81 deg and it is even better if inside an RV where the ambient temp is down in the 70's.

Larry