I am in the construction field and know alot about electrical. There are basically two amperages that the common home in the US uses for standard wall outlets in 120V range, that's 15A and 20A. Your 15A outlets were designed to power things such as lights, tv ,vacuum cleaner etc. 20A circuits are found in the kitchen and most baths. Those are meant for powering appliances and heated objects. A typical hairdryer of today can draw as much as 12 Amps. 12 amps on a 15 amp circuit is considered "maxed out " and possibly overloaded. I person should never run a hair dryer from a 15A outlet or they run the risk of fire. Circuit breakers were designed to "Trip" when the breaker gets overloaded but that does not protect then actual outlet from going into thermal meltdown as you found out! It is easy to tell a 15A outlet from a 20A outlet simply by looking at it! Standard 15A outlets will have (2) verticle lines side by side and a round hole under them. 20A outlets also have (2) vertical lines and a round hole under them but on the left side vertical line there is a small horizontal line that attaches to it creating a "side ways T" shape. If you are unsure which is which contact a local qualified electrician! hope that helps????