How to Trace a Short Circuit

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The term short circuit is often used pretty liberally to refer to a whole range of electrical issues and malfunctions. However, a short circuit specifically occurs when a circuit is configured in a way that allows current to travel down an unintended path. Often, whatever wire or path the electrical current heads down is "short" in that it has a low electrical resistance. The sudden influx of so much current can result in a spark or a blown fuse.

How Do These Occur?

Short circuits usually happens when a hot wire touches any of the other two wires in your fuse box. This causes extra current to flow through the circuit, which causes the circuit breaker to trip or the fuse to blow. However, this is not the only reason for short circuits to occur. There are many potential problems in electric circuits, such as faulty wiring, broken insulation, circuit overload, as well as defective plugs, switches, cords, and receptacles. One can take place in both direct and alternating current circuits.

  • Warning: Short circuits can be dangerous, as they can produce very high temperatures due to the high current flow through the circuit, which may cause the wire to explode and catch fire. This same principle is applied deliberately in the world of arc welding, which uses electricity to generate huge amounts of heat.


The use of safety fuses and circuit breakers, which disconnect the electricity in reaction to an excessive current, can often reduce the damage that a short circuit can cause and are also helpful in isolating the exact location of the short circuit.

Sometimes though, it's still not possible to know the cause of the short circuit. It's easy to see if a short circuit has occurred, but pinning down the exact position of the short circuit within the larger electrical system can be difficult.

If you suspect a short circuit has a occurred, you can test this by turning on a switch or plugging in a particular electrical appliance. If doing so causes the lights in the rest of the house to go out, then it's a short.

Tracing a Short Circuit

Step 1 - Power Down

To trace a short circuit, all the electrical switches should be turned off. All lights and other electric appliances should be unplugged. The tripped circuit breaker should be reset. A replacement should be completed if there is a fuse instead of a circuit breaker.

Step 2 - Check Receptacles or Switches

After resetting the breaker, if it trips again immediately, there is a possibility of a short circuit in a receptacle or a switch.

Step 3 - Narrow it Down

If the circuit breaker does not trip, turn on each switch one at a time until the breaker trips again. When the breaker trips upon turning on a particular switch, it is evident that there is a short circuit in a fixture or receptacle controlled by the switch.

Step 4 - Identify a Particular Electrical Appliance

When the circuit breaker does not trip even after turning all the switches on, then you can conclude that the original problem started with an electrical appliance somewhere inside the home. Return to the electrical appliances and lights and begin plugging them in one by one. As soon as the breaker trips, whichever appliance is plugged in at that moment can be identified as problematic and isolated.

The issue could lie in the plug, the cord, or the appliance itself.