Electrical Systems

Troubleshooting: Electrical Faults 330

This class describes the most common types of electrical faults and their causes, as well as the hazards they present. The most common types of electrical faults are open circuit faults and short circuit faults. Open circuit faults involve broken components that prevent current from flowing through a circuit. Short circuit faults involve current straying away from its intended path. Short circuit faults are much more dangerous than open circuit faults, but there are several types of safety devices designed to prevent or limit their effects.

After taking this class, users will be able to describe and distinguish between open circuit and short circuit faults, as well as the most common causes of each type of fault. They will also understand the specific hazards created by electrical faults and how common safety devices protect against them.

  • Difficulty Advanced

  • Format Online

  • Number of Lessons 9

  • Language English


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Course Outline
  • Electrical Faults
  • Open Circuit Faults
  • Causes of Open Circuit Faults
  • Review: Open Circuit Faults
  • Short Circuit Faults
  • Causes of Short Circuit Faults
  • Hazards of Short Circuit Faults
  • Protective Devices
  • Review: Short Circuit Faults
  • Define electrical faults.
  • Describe open circuit faults.
  • Describe common causes of open circuit faults.
  • Describe short circuit faults.
  • Describe common causes of short circuit faults.
  • Describe the hazards created by short circuit faults.
  • Describe safety devices that protect against electrical faults.
Vocabulary Term


The amount of current flowing in a circuit. Amperage is measured in amperes (A), or amps.

arc fault

A short circuit fault that occurs when an electric arc forms between exposed conductors. Arc faults can produce arc flash.

arc fault circuit interrupter

AFCI. A type of circuit breaker that immediately disables a circuit if it detects an arc fault. Arc fault circuit interrupters detect the specific electrical frequencies generated by arc faults.

arc flash

An electrical explosion that can occur when an electric arc creates a short circuit between exposed conductors. Arc flash can produce enough heat, light, and explosive force to cause permanent injury or death.

circuit breakers

An overcurrent device with a bimetallic strip that bends and trips a switch to open a circuit. Circuit breakers can usually be manually reset and re-used multiple times after triggering.


A controlled path for electricity. A circuit includes a source, path, load, and control.


A material that allows the free movement of electrons and therefore enables the easy flow of electricity. Conductors are typically metals.


The state of having a complete path that allows the uninterrupted flow of electricity. Continuity can be tested with a multimeter.


The flow of electricity through a circuit. Current requires a complete, or closed, circuit to flow through.

disconnect switch

A control device used to separate an electrical circuit from its supply of electrical energy. The disconnect switch should be used to de-energize a circuit before beginning maintenance or repair work.

electric arcs

The area in which electricity passes through the air from one conductor to another. Electric arcs can produce extreme heat and light.

electric shock

The flow of electricity through the body. Severe electric shock can be fatal.

electrical box

A metal cabinet in a building where power from the electrical distribution system enters and is distributed throughout the building. The electrical box connects to every circuit and electrical device in the building.

electrical fault

Any condition that causes an abnormal flow of current in a circuit. Common types of electrical faults include open circuit faults and short circuit faults.

electrical fire

A fire involving energized electrical equipment. Electrical fires are very dangerous because they put employees at risk of electric shock in addition to burns.

electrical outlets

A socket that allows electrical equipment to be connected to a building's electrical system. Electrical outlets sometimes contain built-in circuit breakers.

extension cords

A flexible, insulated conductor used to extend the range of a power cable. Extension cords are subject to frequent wear and damage.


The number of complete alternating current cycles that occur in one second. Frequency is measured in hertz (Hz).


An overcurrent device with a metallic component that melts to open a circuit. Fuses can only be used once and must be replaced after the metal component melts.


A source of zero electrical potential, such as the earth or another large conducting body. A ground absorbs electrical currents.

ground fault circuit interrupter

GFCI. A type of circuit breaker that disables a circuit when it detects a ground fault. Ground fault circuit interrupters are often built into outlets to help prevent electric shock.

ground faults

A short circuit fault that creates an unintended path to the ground. Ground faults put employees at high risk of electric shock.


A material that does not conduct electricity and is used to cover electrical conductors. Insulation may be made of rubber, plastic, or ceramic.


A component in a circuit that converts electricity into light, heat, or mechanical motion. Examples of loads include light bulbs, appliances, and machines.

melting point

The temperature at which a material changes from a solid to a liquid. Melting point varies based on the properties of the material.


A device that is used to measure voltage, amperage, and resistance in electrical circuits. Multimeters can be used to detect and troubleshoot electrical faults.

open circuit faults

A type of electrical fault that prevents current from flowing through a circuit. Open circuit faults are often caused by broken wires or malfunctioning switches.


Excess current flowing through a circuit. Overcurrent conditions can cause circuits to overheat and catch fire.

overcurrent device

A component that protects circuits from excess current flow to prevent overheating and fires. Overcurrent devices include fuses and circuit breakers.

personal protective equipment

PPE. Any clothing or device worn to minimize exposure to hazards and prevent injury. Personal protective equipment for electrical work may include insulated hard hats, insulated gloves, and insulated boots.


A conductor in an AC power system with its own specific voltage. Most AC power systems are three-phase.


AC power that consists of multiple overlapping voltages. Polyphase electrical systems usually have three phases, but some have two phases.

power tools

A tool that is powered by an external source of energy. Power tools are commonly powered by electricity supplied by batteries or a building's electrical system.

qualified employees

An employee who is trained to perform energized electrical work. Qualified employees receive training specific to their job duties as well as advanced training on electrical hazards.


The opposition to current flow. Resistance is measured in ohms (Ω).

root cause

The true origin of a problem, as opposed to any resulting symptoms or effects. Identifying the root cause of a problem is an important aspect of troubleshooting.

short circuit faults

A type of electrical fault that causes current to flow along an unintended path. Short circuit faults can be caused by damaged insulation, unintentional contact between conductors, or water coming into contact with circuits.


A control device that can make or break a circuit by closing or opening. Switches can be manual, mechanical, or automatic.


AC power that consists of three overlapping voltages. Three-phase power is used for all large AC motors and is the standard power supply that enters homes and factories.


A silver-white metal that is very soft and has a relatively low melting point. Tin is often used in fuses.


The systematic elimination of the various parts of a malfunctioning system, circuit, or process to locate the source of the problem. Troubleshooting an electrical circuit often involves conducting visual inspection, consulting electrical prints, and using electrical testing instruments.


The electrical force or pressure that causes current to flow in a circuit. Voltage is measured in volts (V).


Not allowing any liquids to penetrate. Watertight electrical circuit components help prevent short circuits caused by water.


The erosion of material as a result of friction, use, or environmental conditions. Wear is often caused by two or more objects rubbing or sliding against each other.


A bluish-white metal that is corrosion-resistant and has a relatively low melting point. Zinc is often used in fuses.