[86 ssinit]

Hey Shaun I am also an electrician. I think you are right that it is the outside breaker it is showing rust. That outside breaker is your main feed being fed from your meter pan. It's live until your power company kills it which unfortunately for you means they have to shut it off for it to be replaced.
If you want to check your amperage use you will need an amp probe. Open up the panel in the house and with the dryer and the other device on put the amp probe on each of the main feed wires. Each one will give you a reading of the amperage in use. If one is a lot higher than the others shut off that 2nd device on the 30amp breaker. See if the amperage goes down if it does move that 30 amp breaker to one of the other 2 feeders(the one with the least amperage) and that should solve your problem.
Again I think it's the outside breaker.