Home Wiring Short Circuits

Problem: Power to a circuit is cut off by a fuse or circuit breaker in the main panel.

Background: If a fuse is blown, the fuse window will appear discolored and the metal strip running across the inside of the window will be bro ken. This indicates a short circuit caused by either 2 bare wires touching, or by a hot wire grounding out to a metal object somewhere in the circuit. Circuits protected by cartridge fuses will give no visible indication that a short circuit has taken place. Tripped circuits protected by circuit breakers can be identified when the handle of the circuit breaker is in the “tripped” or “off” position.

What to do: If the circuit power cuts off and no fuse appears to be blown. The method for identifying the cause of a short circuit is the same for fuses or circuit breakers. Disconnect all lights and appliances on the circuit with the blown fuse or tripped circuit breaker. Then replace the blown fuse or turn on the tripped circuit breaker. If the fuse blows or the circuit breaker trips with all appliances unplugged from the circuit, the short is in the circuit wiring itself and the wiring must be repaired or replaced. If the circuit is good, reconnect each light and appliance on that circuit, one at a time.

Special advice: Use extreme caution when reconnecting lights and appliances. Do not connect suspiciously frayed cords to outlets. When you turn on the faulty light or appliance, the fuse will blow or the breaker will trip again. Carefully check appliances for bare cords, broken light sockets, or damaged plugs before replugging.

Helpful hint: If one particular fuse blows several times, shut off all wall switches and appliances on that circuit, and remove all line cords from the sockets. Remove the fuse and screw a 100-watt light bulb into the fuse receptacle. If the bulb lights with all appliances unplugged from the circuit, a short exists within the circuit. If it doesn’t light, connect each of the appliances, lamps, and line cords one at a time. If the bulb lights at the fuse panel and the appliance fails to work, you’ve located the short. Remove the bulb from the panel before disconnecting the faulty appliance.