A short circuit is a breakdown in an electric circuit caused by the accidental detour of current through a path of relatively low resistance – as occurs when two wires with frayed insulation touch. In a house circuit, the resulting surge of current will blow a fuse (or trip a circuit breaker) or burn out a wire, causing the circuit to go dead .
In a lower power circuit, such as the wiring in a car, a short circuit may not blow a fuse but may simply cause the part of the circuit beyond the short to go dead.
There are three main dangers from short circuits: damage to delicate electric components; shock (for example, when a bare wire touches the metal shell of an appliance, a person touching that appliance receives a shock); and fire caused by sparks or overheating wires. Proper fuses or circuit breakers on a line protect against the last two hazards; appliances are usually protected by their own fuses.
To find a short circuit, test the circuit with all appliances and lamps unplugged and all switches on. If the circuit breaker trips again or a new fuse blows, the trouble is in a switch, receptacle, or the wiring. Open and inspect switch boxes and receptacles. If you see charred parts on a switch or receptacle, replace it. If you see a burned wire, a bare wire touching the metal housing, or a wire with a break in its insulation, rewire, using wire connectors. Don’t use electrician’s tape to reinsulate frayed wires.
If the circuit works, plug in and turn on appliances one by one until you discover the faulty device. Unplug it and have it repaired.
If the problem is in the house wiring itself, get an electrician to track it down and make the repair.