An electrical circuit is a circular flow of energy from a home’s electrical service panel and back again. This flow is continuous and unbroken. Items along the circuit such as outlets and lights only borrow from the circuit; they do not break the circuit. Electricity likes to flow along the path of least resistance. Copper is used for electrical wires because it conducts so well, while materials like wood or fiber would be highly inefficient materials for wiring because they resist electricity. Even steel and iron are poor materials for wiring, though better than wood or fiber. The long path for the energy to flow back to ground is on the circuit. But when a shorter path is provided, electricity naturally seeks this route—the path of least resistance. The electricity immediately changes its course to head to ground by this shorter, easier path.
What Causes Short Circuits
Short circuits can be caused by:
Vermin or pests chewing through wires Water or other fluids coming into contact with electrical wiring Loose connections in an electrical box Old or damaged outlets, switches, lights, appliances, or other electrical devices Nails or screws piercing through walls and coming into contact with wires Deterioration of electrical cable sheathing Build-up or surges of electricity
Types of Short Circuits
Normal Short Circuit
In a normal short circuit, a powered or hot wire touches a neutral wire. Immediately, resistance drops and current begins to move in another path.
Circuit breakers or fuses detect changes in electrical current flow, breaking the circuit connection when it detects an irregularity. Ground-fault circuit interrupters are also sensitive to changes in electrical current flow, automatically shutting off the current’s flow in case of fluctuations. Arc-fault circuit interrupters protect against arcs or jumping electrical currents that can cause a fire. They also shut the power off, anticipating an imminent short circuit.
Ground Fault Short Circuit
In a ground fault short circuit, a powered or hot wire touches a grounded section of a box, device, appliance, outlet, bare ground wire, or anything else supplied by the electrical circuit.
Signs of a Short Circuit
Previous Short Circuits
Short circuits often do not announce themselves until the moment they happen. In some cases, though, there may be a warning sign of a previous short circuit. This may be in the form of a charred wire or light switch. If the short circuit was recent, you may sense a metallic smell. Or you may smell burned plastic or rubber.
Ongoing Short Circuits
A clear sign you know a circuit has shorted is when the circuit breaker usually shuts off. Sometimes, there are sparks and a bright light. A loud zapping sound or a boom can accompany a short circuit. The device powered by the electrical current stops working. GFCI outlets will trip off. If you are touching the device or if your body happens to be the short within this short circuit, you may receive an electrical shock and often a burn from the intense heat.
Why Short Circuits Are Dangerous
When the human body is introduced as the path of least resistance, the current travels through the body. A short circuit is harmful because it can cause injury or death through electrical shock, electrocution, or fires. More power is demanded during a short circuit, causing electrical arcs and extremely high temperatures that can melt plastics or set fire to flammable materials such as wood or fabrics.
How to Fix Short Circuits
When to Call a Professional
For many homeowners, short circuits can be difficult to find and fix. Call a licensed, qualified electrician for help if you encounter any difficulties.
