Ground Fault vs Short Circuit: What's the Difference?

Ground faults and short circuits are electrical problems that can cause the same problem: a circuit that suddenly goes dead, causing lights and appliances to stop working.

The two are closely related but different. A short circuit happens when a hot or electrified conductor contacts a neutral or ground conductor. A ground fault happens when an energized conductor unintentionally touches the equipment frame or the ground.

Ground Fault vs. Short Circuit: Similarities & Differences

Short circuits and ground faults involve hot wires but differ in what the wires touch.

• Short circuit: The hot and neutral wires touch.
• Ground fault: The hot wire touches the ground.

Both short circuits and ground faults will result in blown fuses or tripped circuit breakers. If a ground fault happens, your GFCI outlet will act as an alert. But in a short circuit, you may be alerted by smoke or sparks.

Damaged wiring can cause either a short circuit or ground fault. Loose connections in the electric service panel or fuse box may cause short circuits, while overloaded circuits can result in ground faults.

What Is a Ground Fault?

An electrical system can experience a number of different types of faults—defined as any abnormal flow of electricity. A ground fault is a type of fault in which the unintentional pathway of the straying electrical current flows directly to the earth (to the ground).

Electrical Definition

A ground fault occurs when a hot wire contacts either the grounding wire or a grounded portion of the system, such as a metal electrical box. A ground fault causes the circuit breaker to trip due to the uncontrolled flow.

In a sense, a ground fault is a "short" circuit in that it has bypassed the circuit wiring, so it can technically be defined as one type of short circuit.

Danger

The main danger of ground faults comes in the likelihood of shock if a person happens to be in contact with the path of least resistance to the ground. This is why the danger of shock is much more pronounced in situations where a person is standing on the ground or in a damp location.

Signs

Signs of a ground fault include tripped circuit breakers, flickering lights, a burning smell near electrical sources, or clicking and buzzing sounds coming from outlets.

Protection

Protection against ground faults is offered by circuit breakers that trip if the flow of electricity suddenly increases, and by a system of grounding wires in the circuits that provide a direct pathway back to ground should current stray outside its established circuit wiring.

There are also ground-fault circuit interrupter outlets that can be used in situations where ground faults are particularly likely, such as in outdoor locations, near plumbing fixtures, and in below-grade locations.

What Is a Short Circuit?

With a short circuit, a hot wire touches a neutral wire. For example, a hot wire may loosen from its connection and contact the neutral wire or vice versa.

Electrical Definition

A short circuit is any electrical flow that strays outside its intended circuit with little or no resistance to that flow. The usual cause is bare wires touching one another or wire connections that have come loose.

Danger

Short circuits can occur when insulation on wires melts and exposes bare wires. The principal danger of a short circuit is arcing or sparking, which may occur as electrical current jumps from a hot wire to a neutral. This situation can easily cause fires.

Short circuits can also occur within the wiring of individual devices, such as lamps or other plug-in appliances. Frayed or otherwise damaged electrical extension cords or appliance cords can also cause short circuits.

Signs

The immediate impact of a short circuit is that a large amount of current suddenly flows. This causes the circuit breaker to trip, instantly stopping all current flow.

This condition is known as a short circuit because the current bypasses the full circuit wiring and flows back immediately to the source by a shorter pathway.

Protection

Circuit breakers provide protection against short circuits. They trip and shut the circuit off when current begins to flow uncontrolled.

A special type of circuit breaker, an arc-fault circuit interrupter (AFCI) is now commonly used. It senses arcing, or sparking, and shuts off the current even before the current flow overloads the breaker.

Causes of Ground Faults and Short Circuits

Ground Fault Causes

• Water: Water leaking into an electrical box can cause a ground fault, since water is a conductor of electricity.
• Wires touch: Worn hot wires or hot wires that are not completely seated into their terminals may touch ground wires or grounding devices or boxes.
• Tools/appliances: Power tools or appliances without proper insulation can cause a ground fault if faulty wiring causes current to flow directly to ground.

Short Circuit Causes

• Loose connections: A short circuit may be caused by a loose connection on one of two wires in a junction box or outlet box or incorrect wiring.
• Wire off terminal: A short circuit can occur when a wire slips off of a terminal on an electrical device, such as an outlet. When it touches another wire, a short circuit ensues.
• Appliance: An appliance may encounter an internal wiring problem, causing hot and neutral wires to accidentally touch.
• Damage from pests: Insects or rodents may chew the wire insulation and cause a short circuit between two wires within a cable bundle.

When It's a Ground Fault or a Short Circuit

If you fail to turn off the power to the circuit before working on it, short circuits and ground faults can occur.

Bare wires can touch the wrong places. When a hot wire touches a neutral wire, the resulting short circuit can cause sparks to fly.

A ground fault will occur when a hot wire contacts a grounding wire or a grounded metal box. Sparks may result, and shock and injury are also possible.