The size of electrical wire is dependent upon the amount of current required to operate a particular appliance. Electrical circuits in homes are designed so that all components are compatible. The size of the wire, outlets and circuit breakers are designed for an anticipated electrical load. A circuit is said to be overloaded when too much current flows causing heat build up or wiring to break down. This can lead to sparks and fire.
Deteriorated insulation is one of the most frequent causes of short circuits.
They are set at a specific amperage. When that amperage is exceeded, it trips and shuts off the flow of electricity, stopping the circuit from continued overheating. When a fuse or circuit breaker trips, it is important to find the cause and correct it. Often, people will just reset the breaker or put in larger fuse. When a house is under construction, city inspectors visit to make sure the electrical system is in compliance with the City Building Code and the National Electrical Code.