Likely you would flip a breaker if anything. If I am not sure, I run a hairdryer on low heat. Fan speed has little effect but heat takes a lot of power. A good hairdryer has independent controls for fan speed and heat. A crummy one doesn't. Somme high-priced ones are crummy.
Here's what also could happen. You flip a breaker. That breaker is also the one for the engine horn. The engineer can no longer sound the horn so hits a truck which bounces up knocking out the antenna so the engineer can't tell dispatch he hit the truck. Just then a piece of the truck falls on the brake control preventing the engineer from applying the brakes. He now has a runaway train so it blasts through all the signals. The dispatchers realize this so they sideline all the trains to allow yours through. You fly through intermediate stops. Meanwhile the SCA finds the flipped breaker and resets it. Your wife has decided the hairdryer had a problem so she flips the switch to low heat just as the breaker is reset. she happily dries her hair. While this is going on, everyone is complaining to the conductor that they missed their stations so the conductor is kept busy handing out vouchers and calling the office to arrange new connections.
The diner staff realizes they will not feed everyone so they quickly shove the food onto the tables to get everyone fed before final destination. Unfortunately, since that breaker also controlled the convection oven, the food is still frozen. Three people break a tooth and one discovers frozen chicken would make a good new ice cream flavor for Baskin Robbins. He calls his attorney to patent the idea only to find out a fellow passenger beat him to it. They get into a fist fight. Someone calls the police on their cell phone.
The local police arrive and park their cars on the tracks, jump out and draw their guns not realizing the train can't stop. When they realize it won't, they deploy stop -sticks to deflate the tires not realizing it doesn't work with steel wheels. However, the brake line breaks from a flying piece of stop-stick releasing the air and locking the brakes bringing the train to a halt just as it arrives in your station. Your SCA announces that you need to get off and you and your wife, happily with dry hair, exits the train. You report here that your train arrived early and everything worked out.
As you leave you can't understand why people are complaining, the engineer is kissing the ground, the police are dragging two men off the diner and the diner staff is exhausted. No big deal. Just another typical Amtrak day.
Don't let it bother you that she just HAS to use the hairdryer.