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How to Identify a Short Circuit or Overload

Diagnosing the cause of a tripped circuit can be tricky; fortunately, the repair is usually easy.

Home electrical circuits may have a number of problems: faulty wiring within the house, too many lamps or appliances on one circuit, defective wall switches or receptacles, defective cords or plugs, or defective circuits within appliances. Short circuits happen when a hot wire touches a neutral or ground wire; the extra current flowing through the circuit causes the breaker to trip or a fuse to blow.

Although it’s often easy to tell when you have a short or overloaded circuit—the lights go dead when you plug in the toaster oven—it isn’t always as simple to tell where in the electrical system this has occurred.

To diagnose the problem, start by turning off all wall switches and unplugging all lights and appliances. Then reset the circuit breaker. Flip the breaker switch to off and then to on again to reset a circuit breaker.

circuit breakers© HomeTips

Look inside the electrical panel for a circuit breaker that has flipped off.

If a fuse is blown, it must be replaced. Unscrew the fuse to replace it with one that has exactly the same amperage rating (both circuit breakers and fuses should be sized according to the wire used in the circuit they protect).

changing an electrical fuse© HomeTips

If your circuits are protected by fuses, remove and replace those that are blown.

If the breaker trips immediately, the problem may be a short in a receptacle or switch. If the breaker does not trip again, turn on each switch one at a time and check if and when the breaker trips again.

If turning on a switch causes the breaker to trip, there’s a short circuit in a fixture or receptacle controlled by the switch. If turning on the switch makes no difference, the problem is in one of the appliances connected to the switch.

If the circuit went dead when you plugged in the appliance, the problem is probably in the cord or plug. If the circuit went dead when you turned on the appliance, it’s likely that the appliance itself is defective.

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About Don Vandervort
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Don Vandervort has developed his expertise for more than 30 years, as Building Editor for Sunset Books, Senior Editor at Home Magazine, author of more than 30 home improvement books, and writer of countless magazine articles. He appeared for 3 seasons on HGTV’s “The Fix,” and served as MSN’s home expert for several years. Don founded HomeTips in 1996.

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