No Brian, you didn't do anything wrong. There is suppose to be a safety built in to prevent what happen. Either a transfer switch which will only allow power to come from 1 source failed or your 110 power from the house was low and the transfer switch wasn't able to operate as it should. the key to look for is what happen when you turned the air on. Low voltage from the house may have been your problem. {15 amp/ 30 amp} If it was 15 amp circuit then remember the ac draws somewhere around 14 amps when running. Just my thoughts.