What Causes an Electrical Short Circuit?

A “short circuit” is what happens when a connection with very low resistance forms between two conductors in a circuit. This connection leads to a surge in current flow and a drop in voltage from the power supply. Electricity always takes the shortest possible route from one wire to another, or from a wire to ground. This is why we call it a “short” circuit, as electricity has found a shorter path to take than what was intended. 

Electricity naturally follows the path of least resistance. Materials called insulators are what surrounds the wire, keeping electrical current inside of the copper. In certain scenarios, such as when electrical wiring is damaged and loses its insulation, or the wiring becomes loose, electrical current may find its way out of the intended circuit. This leads to what we call a “short”.

 

Causes of an Electrical Short Circuit

 The most common reasons for electrical short circuits include the following:  

• Wires being chewed through by pests or vermin

• If an electrical wire comes in contact with water or other fluids

• Faulty connections in the electrical wiring of appliances

• Old or damaged outlets, switches, lights, appliances, or other electrical devices

• Abnormal build-up of electrical currents

• Walls pierced by nails or screws that come into contact with live electrical lines.

To understand why short circuits occur and how to avoid them, it’s important to start with a basic understanding of how electrical circuits are made and how they function within your home. 

Basic Concepts

Electricity is distributed through your home via a network of wiring that carries electric current from the main power supply to various outlets, fixtures, and appliances. Each circuit in your home is a loop, where the black wire (hot wire) from your electrical breaker carries electricity out to your home, and the electrical current then returns back to your panel on the white (neutral) wire. 

Your wiring is made up of the following parts: 

• Copper or Aluminum metal, acting as the conductor

• Insulation which surrounds the wire, preventing the escape of electricity

• A typical wiring setup is one black (hot) wire, one white (neutral) wire, and one bare copper wire which we call the ground.

There are three basic properties of electricity, shown below: 

• Current: The flow of electrical charge, measured in amperes (amps). It’s what powers your devices and lights.

• Voltage: The pressure from the power source that pushes the current through the wires, measured in volts.

• Resistance: The opposition to current flow within circuits, measured in ohms. The insulation surrounding your wires creates resistance, blocking electricity from going places we don’t want.

When resistance from your black (hot) wires to an area that should not carry electricity is low enough, a short circuit is created. 

Types of Short Circuits

Normal Short Circuit

The typical short circuit occurs when a hot (black) wire touches a neutral (white) wire. As a result, the resistance in the circuit will decrease immediately, and a large amount of current will flow in the circuit.  

Ground Fault Short Circuit

A ground fault short circuit happens when a hot wire comes in contact with a grounded piece of metal or a wet object. A metal wall box that is grounded, bare ground wire, or the metal shell of an appliance are all examples of this.

 

Both of these situations are potentially dangerous! The increased current flow caused by a short circuit can generate sparks and enough heat to melt metal. Imagine what this could cause inside the wooden frame of your home. 

Signs of an Electrical Short Circuit

A Burning Smell or Burn Marks on Outlets If an outlet displays burn marks or emits a burning smell, it could indicate a short circuit. This could occur due to many different factors, each of which is a potential fire hazard.

Buzzing and Popping Noises Be alert for buzzing or popping sounds from an outlet, which might suggest an overloaded circuit, faulty outlet or loose connections and may lead to a short circuit with obvious safety concerns. 

Sparks from the Circuit Observing sparks or electrical arcs emitted from a circuit is a clear sign of a potentially dangerous short circuit situation. This may not indicate a short, but it does indicate an immediate safety concern. 

Tripped Circuit Breakers or Blown Fuses: These safety devices may activate to cut off power, preventing further damage or fire. These are not always signs of a short circuit, an occasional breaker trip is normal. But if it happens consistently there may be a more serious problem that requires the services of an electrician. 

Preventing Short Circuits

Keep your eyes open for any signs of faulty outlets or wiring. Regular inspections of your electrical wiring system are highly recommended to ensure long term safety of your family and property. Short circuits can occur due to damaged wires, loose connections within junction boxes, faulty appliances or outlets that are aged or heavily used. They may also occur due to ingress of water into electrical boxes, panels, switches & outlets. Promptly addressing, or better yet avoiding these issues by inspecting, repairing or replacing your electrical equipment is essential. Up to 20% of residential fires are caused by electricity and it’s best to minimize the risk. 

You can cut down the risk of fire and short circuits by avoiding the use of power bars or splitters on an outlet and by not overloading individual plugs. Also, if you are unsure what you are doing, don’t touch it! DIY electrical work and poor quality renovations are a common cause of short circuits and electrical fires. Hire a professional Calgary Electrician to provide advice if you are considering performing electrical work in your home. 

Also, installing certain devices can further safeguard against electrical short circuits. Your home may already have some of these installed, especially if it was built to modern electrical codes. These include: 

• Fuses: These devices protect against excessive current. They contain a metal strip or wire that melts when exposed to high currents, thereby breaking the circuit to prevent the flow of electricity.

• Circuit Breakers: These are designed to interrupt the flow of abnormal currents in a circuit. They detect unsafe rises or fluctuations in current flow and open the circuit, providing indication that there may be a problem.

• Poly Switches or Resettable Fuses: Also known as poly fuses or multi-fuses, these components prevent overcurrents in electronic circuits without needing replacement.

• Residual Current Circuit Breakers (RCCBs) or Residual Current Devices (RCDs): These devices quickly detect faults in the power supply and shut it down within milliseconds to prevent electric shocks.

• Inrush Current Limiters: These components limit the initial surge of current to protect appliances and prevent fuses from blowing. They are most commonly found on the circuit boards of appliances and other electronic equipment.

• Lightning Protection: There are many different forms of lightning protection available, from whole home or building systems to smaller forms such as those made from metal oxide varistors (MOVs), these items act as protection for electronics, preventing power surges from damaging sensitive electronic components. Often found in appliances and computers.

• Ground-Fault Circuit Interrupters (GFCIs): GFCIs monitor and compare the inflow and outflow of electricity in a circuit, disconnecting the power if they detect a ground fault or an imbalance.

• Arc-Fault Circuit Interrupters (AFCIs): AFCIs swiftly cut off power to a circuit upon detecting an arc, significantly reducing the risk of electrical fires.

What Happens When There is a Short Circuit?

Short circuits are not just minor inconveniences; they pose serious risks to both safety and property. If you find that a breaker in your panel is tripping constantly then it is best to stop immediately and call a Calgary Electrician, resetting the breaker over and over may be causing sparks to fly inside your home! Knowing the effects of a short circuit is important to an understanding of why preventive measures and a timely response is needed. 

Immediate Effects

When a short circuit occurs, several reactions take place that can have bad effects on your electrical system and safety: 

• Current flow rises dramatically. In mere milliseconds an outlet or appliance can be exposed to many times more current than it is designed for.

• Massive heat is generated. The rapid increase in current generates heat at the point of contact which in some situations can be enough to weld or vaporize metal.

• Arcing & sparking often occurs. These flashes and sparks are pure electrical energy, sometimes mixed with particles of molten metal. Hot enough to burn skin, wood & drywall with ease.

In the moments after a short circuit is created, there are secondary effects: 

Tripping of Circuit Breakers 

• Designed as a safety mechanism, circuit breakers detect the sudden surge in current from a short circuit and disconnect the electrical flow. This action helps prevent further damage to the electrical system and reduces the risk of fire.

Blowing of Fuses 

• Similar to circuit breakers, fuses act as a protective barrier against electrical overload by melting their metallic wire, which stops the current flow. While effective, blown fuses need to be replaced, unlike circuit breakers which can be reset.

Damage to Electrical Components 

• The surge of electrical energy which occurs can easily damage outlets, melt switches, burn circuit boards and toast appliances.

Sparks or Flames 

• The intense and sudden increase in energy during a short circuit can produce sparks. If these sparks come into contact with flammable materials—such as curtains, carpets, or furniture—they can ignite and lead to a fire. Believe it or not, your home can become fully ignited within 3 minutes.

Long-Term Risks

The immediate effects of a short circuit, if not adequately addressed, can lead to more severe long-term issues within the home: 

Potential for Electrical Fires 

Repeated short circuits can severely damage the integrity of your home’s wiring and electrical components, increasing the likelihood of an electrical fire. Over time, the heat generated by recurring short circuits can weaken protective insulation, leaving wires exposed and more likely to create sparks. 

Damage to Electrical Appliances 

Short circuits can cause significant damage to your appliances and devices connected to the circuit. The surge can fry circuits and ruin motors, leading to costly repairs or replacements. 

Risk of Electrocution 

Short circuits can create unpredictable electrical conditions within the home. For instance, damaged or exposed wiring could energize metallic surfaces, posing a severe risk of electrocution to residents. If you have ever experienced an electrical shock when touching a switch, outlet or other item in your home, we recommend calling for diagnosis and electrical repair as soon as possible. 

How to Prevent a Short Circuit

To reduce the risk of short circuits, homeowners can use several preventive strategies. A proactive approach is key to maintaining electrical safety in your home and ensuring that potential hazards are addressed. 

Avoiding Short Circuits

Inspection and Maintenance 

• Regular Professional Inspections: Engage a licensed electrician to perform regular inspections of your home’s electrical system. Once every 4 years is typical. Performing an inspection can identify potential issues like worn insulation, loose connections, or outdated wiring before they lead to short circuits.

• DIY Checks: Homeowners can perform simple visual checks for signs of wear on cords, outlets, and visible wiring. Look for fraying, discoloration, or damage that could indicate potential problems.

Safety Devices and Installation

• Proper Use of Circuit Breakers and Fuses: Ensure your home is equipped with the correct type and size of circuit breakers or fuses. These devices should be checked periodically to confirm they are functioning correctly.

• AFCI’s: Consider installing arc-fault circuit interrupters (AFCIs) which provide improved safety by detecting and tripping the circuit when an electrical arc fault is sensed. These are common in homes built to modern code, but older homes likely do not have AFCI’s installed.

• Ground Fault Circuit Interrupters (GFCIs): In areas exposed to moisture, such as kitchens and bathrooms, GFCIs can prevent ground faults, significantly reducing the risk of short circuits and electrocution. Your home likely has these installed where necessary, but do you test them for proper function? Manufacturers recommend regular testing and replacement of GFCI’s that do not perform as expected.

What to do When a Short Circuit Occurs

 

Immediate Actions

Power Down: If a short circuit is suspected, immediately shut off power at the breaker panel to prevent further damage or fire. This should be done before any inspection or repair is attempted. 

Inspect the Area: Once the power is off, carefully inspect the area where the short circuit occurred. Look for signs of damage or overheating. Do not touch any electrical components directly; use tools or protective gear if necessary.  

Contact a Professional

Professional Repair: For any suspected electrical issue, contact a qualified electrician (link). Attempting to repair electrical systems without proper knowledge and tools can be dangerous. 

Follow-Up Inspection: After repairs are made, have the electrician perform a thorough inspection to ensure that future risks are eliminated and your home electrical system is safe.

Long-Term Electrical Safety Practices

Education: You got a headstart by reading this article! Ensure that all family members understand the basics of electrical safety. Knowing what signs to look for and how to respond can make a significant difference in preventing accidents. 

Update and Upgrade: The electrical demands of modern life are growing. Consider updating or upgrading your electrical system to accommodate increased loads safely. This includes adding additional circuits or enhancing current protective measures. Defective electrical components, even panels, can be a risk you do not need to take. 

Stay vigilant, stay informed, and never hesitate to take preventive steps or seek professional assistance when it comes to protecting your home from electrical hazards. Our 24 Hour Electricians can help you repair, replace and maintain every piece of the electrical system in your home to keep your family safe.