Electrical Glossary

Electrical Terms

The AB Electrical & Communications electrical glossary is an essential resource for understanding electrical terms and concepts. It covers a broad spectrum of topics, from basic definitions like AC and DC to complex principles like impedance and three-phase power. This guide is invaluable for both professionals and enthusiasts in the field of electrical and communication systems.

AC (Alternating Current) 

Alternating Current (AC) is the form of electrical current that reverses direction periodically. It is the standard form of electricity supplied to homes and businesses, usually at 50Hz. This type of current is efficient for transmitting electricity over long distances, making it suitable for the widespread electrical infrastructure.

AC Load

An AC load refers to any device or appliance that consumes alternating current. It encompasses a wide range of common electrical equipment like refrigerators, air conditioners, and lighting fixtures. The load’s power consumption is measured in watts and should match the standard AC supply voltage, typically 230V at 50Hz.

Active Power

Active Power, measured in watts (W), is the portion of electricity that is actually consumed by devices to perform work. It indicates the rate of energy transfer from the power source to the load, driving functions in devices such as motors and lights. Active power is distinct from reactive or apparent power, as it is directly involved in performing tangible work.


An ammeter is an instrument used to measure the flow of electric current in a circuit, in units of amperes. It is an essential tool for electrical diagnostics and maintenance, ensuring compliance with electrical safety standards. Available in both analog and digital forms, ammeters are widely used in various settings from simple home electrical checks to complex industrial systems.


Ampacity is the maximum amount of electrical current a conductor or device can carry before sustaining immediate or progressive deterioration. It is determined by the conductor’s material, size, and environmental conditions. Understanding ampacity is crucial for the safe and efficient design and installation of electrical systems, ensuring they operate within safe limits.

Ampere (or Amp)

An ampere, commonly known as an amp, is the unit of electric current in the International System of Units (SI). It represents the rate at which electric charge flows through a conductor. One ampere is defined as one coulomb of charge moving past a point in a circuit per second, fundamental in sizing electrical components and safety devices.

Apparent Power

Apparent power, measured in volt-amperes (VA), is the product of the root-mean-square (RMS) voltage and RMS current in an AC electrical circuit. It combines active (real) power, which does work, and reactive power, which sustains the electric and magnetic fields. Apparent power is key in sizing electrical systems, particularly in calculating the capacity of wiring and transformers.

AS/NZS 3000 (Australian/New Zealand Wiring Rules)

AS/NZS 3000, commonly referred to as the Australian/New Zealand Wiring Rules, is the standard that outlines the requirements for the design and installation of electrical systems in Australia and New Zealand. It covers various aspects of electrical installations, including safety, to ensure compliance with regulatory requirements and promote best practices in electrical wiring.


A capacitor is an electrical component that stores and releases electrical energy, functioning based on two conductive plates separated by an insulating material. It can hold an electric charge temporarily and is used in various applications such as stabilising voltage and power flow, filtering signals, and timing circuits. Capacitors are essential in electronic and electrical systems for their energy storage and release capabilities.

Capacitive Load

A capacitive load in an electrical circuit is characterised by the consumption of reactive power, which leads to the current leading to the voltage in phase. This type of load is typical in systems with components like capacitors or inductive ballasts. In electrical systems, managing capacitive loads is crucial for power factor correction and efficient energy consumption.


In electrical contexts, a cable is a set of wires, usually encased in sheathing, that transmits electricity or signals. Cables vary in size, insulation, conductor material, and specific design, depending on their intended application, from small data transmission to large power distribution. The appropriate selection and installation of cables are vital for ensuring safety and efficiency in electrical systems.


A circuit is a complete and closed path through which electric current can flow. It typically includes a source of electricity, such as a battery, conductive wires, and load, such as a light bulb or motor. Circuits can be simple or complex and are fundamental to all electronic and electrical systems. Their design dictates how electrical devices function and interact.

Circuit Breaker

A circuit breaker is a safety device designed to protect an electrical circuit from damage caused by overcurrent or a short circuit. It automatically interrupts current flow after a fault is detected. Unlike fuses, which need replacing after one use, circuit breakers can be reset (either manually or automatically) to resume normal operation, making them an essential component in modern electrical systems for ensuring safety and preventing damage.


In electrical terms, a conductor is a material that allows the flow of electrical current in one or more directions. Common conductors include metals such as copper and aluminium, known for their low resistance to electric flow. Conductors are fundamental in creating electrical circuits, allowing for the transmission and distribution of electricity to power various devices and systems.


A conduit in electrical installations is a tube or trough used to protect and route electrical wiring. Conduits can be made of metal, plastic, fibre, or fired clay and are used to shield wires from damage and reduce the risk of fire or electric shock. They are essential for organising and safeguarding electrical wires, especially in exposed, underground, or wet locations.


In electricity, current refers to the flow of electric charge, typically measured in amperes (amps). It is a fundamental concept in electrical engineering, describing the rate at which electrons flow through a conductor. Current can be direct (DC), flowing in one direction, or alternating (AC), where it reverses direction periodically and is crucial for powering electrical devices and systems.


In electrical terminology, a cycle refers to one complete sequence of alternating current (AC) or voltage going through a rise and fall. In a standard AC system, this involves the current rising to a maximum, falling to zero, reversing, and then returning to zero again. The frequency of these cycles is measured in Hertz (Hz), with one cycle per second equating to 1 Hz.

DC (Direct Current)

Direct Current (DC) is a type of electrical current where the flow of electric charge is unidirectional, unlike alternating current (AC). It is used in applications such as batteries, solar panels, and electronic devices. DC is crucial for its ability to provide a constant voltage or current, making it ideal for low-voltage or sensitive electronic applications.

DC Load

A DC load refers to any device or appliance that operates on direct current (DC). This includes items such as LED lighting, electric vehicles, and electronic devices. DC loads are characterised by their steady consumption of power, as opposed to the fluctuating power usage seen in AC loads. They are integral in systems where stable and continuous power is required.

Demand Factor

The demand factor is a measure used in electrical engineering to estimate the load a system will typically experience compared to its maximum possible load. It is calculated by dividing the actual demand by the total connected load. This factor helps in designing electrical systems to ensure they are both cost-effective and capable of handling the peak demand without unnecessary oversizing.


A diode is a semiconductor device that allows current to flow in one direction only, acting as a one-way valve for electric current. It has two terminals, an anode and a cathode, and is commonly used in electronics for tasks like rectifying alternating current to direct current, isolating signals, and regulating voltage. Diodes are key components in power supplies, radios, and digital electronics.

Diversity Factor

Diversity factor is a concept in electrical engineering, referring to the ratio of the sum of the individual maximum demands of various subsystems to the maximum demand of the complete system. It accounts for the fact that not all electrical devices operate at their maximum load simultaneously. This factor is used to design more efficient and cost-effective electrical systems, ensuring adequate capacity without significant oversizing.


Earthing, also known as grounding, involves connecting the metallic parts of an electrical installation to the earth. This practice is a critical safety measure that prevents electric shock in the event of insulation failure or other faults. It ensures that in case of a fault, the current will have a low-resistance path to the earth, significantly reducing the risk of electric shock or fire.

Electric Shock

An electric shock occurs when a person comes into contact with an electrical energy source, allowing current to flow through the body to the ground or another part of the electrical circuit. This can result in anything from minor discomfort to serious injury or even death, depending on the current’s magnitude, path through the body, and duration of contact. Electrical safety measures are crucial to prevent such incidents.

Electrician’s Licence

An electrician’s licence is a mandatory credential required for individuals to legally carry out electrical work. This license signifies that the holder has met certain education and training requirements and has demonstrated competence in handling electrical installations, repairs, and maintenance safely and effectively. Different types of licenses may apply for various levels of work, from apprentice to master electrician.

Electrical Current

Electrical current is the flow of electric charge through a conductor, typically measured in amperes (amps). It can occur in two forms: direct current (DC), where the flow of charge is in a single direction, and alternating current (AC), where the charge periodically reverses direction. Electrical current is fundamental in powering electronic devices and electrical systems.

Electrical Tape

Electrical tape is a type of pressure-sensitive tape used to insulate electrical wires and other materials that conduct electricity. It is typically made from slightly stretchy PVC or vinyl and is designed to endure environmental factors such as moisture and varying temperatures. Electrical tape is essential for safely and effectively completing electrical installations and repairs, ensuring insulation and preventing electrical hazards.


An electron is a subatomic particle with a negative electric charge, found in all atoms. Electrons orbit the nucleus of an atom and are fundamental to electricity, as the flow of electrons through a material forms an electrical current. The movement and behaviour of electrons under various conditions are the basis for much of modern electronics and electrical theory.


In electrical terms, frequency is the number of times a periodic event, such as an alternating current (AC), completes one full cycle of rise and fall within a second. It is measured in hertz (Hz). The standard frequency for electricity in most residential and commercial applications is typically 50 Hz, meaning the current changes direction 50 times per second.

Full-load Current

Full-load current refers to the maximum current that an electrical machine or appliance, such as a motor or transformer, can draw while operating at its rated capacity. It is a critical factor in sizing conductors and circuit protection devices, ensuring that the electrical system can handle the load without overheating or causing safety issues.


A fuse is a safety device used in electrical circuits to protect against overcurrent conditions. It consists of a metal wire or strip that melts and breaks the circuit when too much current flows through it, thereby preventing potential damage to the electrical system or fire hazards. Fuses are an essential component in electrical safety, designed to be a fail-safe in the event of electrical faults.

Fused Spurs

A fused spur is a type of electrical supply accessory that creates a new circuit from an existing one, but with its own fuse for protection. It’s often used for heavy or fixed appliances (like dishwashers or washing machines) that require a dedicated supply for safety or functionality. This allows for individual control and protection of the appliance, separate from the main circuit.

GPO (General Purpose Outlet)

A General Purpose Outlet (GPO) is a power outlet designed for everyday electrical devices. It’s a standard fixture in homes and buildings, providing a point where appliances and equipment can be plugged in. The design and specifications of GPOs, including voltage and current ratings, are tailored to suit the general power requirements of a wide range of devices.


In electrical systems, ground or ‘earth’ refers to a reference point in an electrical circuit from which voltages are measured. It’s also a physical connection to the earth, which acts as a common return path for electric current, and a direct physical connection to the ground. Grounding is essential for safety, ensuring stability in the electrical system and protecting against electric shock.

Ground Fault Interrupt

A Ground Fault Interrupt, also known as a Ground Fault Circuit Interrupter (GFCI), is a device designed to quickly shut off an electrical power circuit when it detects that current is flowing along an unintended path, such as through water or a person. This is a critical safety device that helps prevent electric shocks and is often required in areas where electrical circuits may be exposed to moisture.


Hertz is the unit of frequency in the International System of Units (SI) and is defined as one cycle per second. It is used to measure the frequency of alternating currents (AC) and electromagnetic waves. In electrical systems, standard power supply frequencies vary by region; for instance, 50 Hz or 60 Hz are common frequencies for domestic and industrial electrical power.


Impedance is a measure of the opposition that a circuit presents to the flow of alternating current (AC). It is a complex quantity that combines resistance (in DC circuits) with reactance (arising from inductors and capacitors in AC circuits). Impedance is crucial in designing and analysing electrical and electronic circuits, as it affects how much current flows for a given voltage.


An inductor is a passive electronic component that stores energy in a magnetic field when electric current flows through it. Typically consisting of a coil of wire, inductors resist changes in current and are used in various applications, including filters, transformers, and in tuning circuits. They are essential in managing the flow of AC and in creating inductance in a circuit.

Inductive Load

An inductive load in an electrical circuit is one that predominantly uses magnetic fields, such as motors, transformers, and inductors. These loads cause the current to lag behind the voltage because energy is stored in and released from magnetic fields. Inductive loads are significant in power systems as they affect power factor, a key consideration in efficient power delivery and consumption.


An insulator in electrical terms is a material that significantly resists the flow of electric current. Common insulators include rubber, plastic, glass, and air. These materials are used to coat or surround conductors to prevent unwanted flow of current, providing safety and stability in electrical systems preventing short circuits, electrical leaks, and ensuring the safe operation of electrical networks.


A joule is a unit of energy in the International System of Units (SI). It is defined as the amount of work done when a force of one newton moves an object one meter in the direction of the force. In electrical terms, one joule is also the energy transferred or work done when one ampere of current passes through a resistance of one ohm for one second. 

Kilowatt (kW)

A kilowatt is a unit of power equal to one thousand watts. In electrical terms, it’s used to quantify the rate of energy transfer or the amount of work done or consumed. For instance, a device rated at 1 kW uses 1000 watts of power when operating at full capacity. The kilowatt is a standard unit for expressing the power output of engines and the power consumption of electric motors and heaters.

Kilowatt-hour (kWh)

A kilowatt-hour is a unit of energy equal to the amount of energy used by a load of one kilowatt over the period of one hour. It’s commonly used as a billing unit for energy delivered to consumers by electric utilities. For example, if a 100-watt light bulb is used for 10 hours, the energy consumed is 1 kWh. It’s a key metric in understanding and calculating electricity consumption and costs.

Kilovolt-ampere (kVA)

A kilovolt-ampere is a unit of apparent power in an electrical system. It is equal to 1,000 volt-amperes. Unlike real power (measured in kilowatts, kW), apparent power (kVA) also includes reactive power, which is the non-working power used to maintain the magnetic fields in AC circuits. kVA is important in sizing generators, transformers, and UPS systems, as it represents the total power required to operate equipment.

Light Socket Adapter

A light socket adapter is a device that allows different types of light bulbs to fit into a socket not designed for them. It typically changes the size or type of the socket base to accommodate various bulb types. These adapters are useful in situations where the existing light fixture socket does not match the bulb type, enabling greater flexibility in lighting choices without the need for replacing the entire fixture.


In electrical terms, a load refers to any device or appliance that consumes electric power and is connected to a power source. This includes everything from small household appliances to large industrial machines. The load draws electrical energy to perform its function, such as lighting, heating, or motion. The size and nature of the load determine the amount of power required from the electrical supply.

Load Factor

The load factor is a measure of the efficiency of electrical energy usage, calculated as the ratio of the average load to the peak load in a specified time period. It is a key metric in power system engineering, reflecting how consistently power is being used. A higher load factor indicates more efficient use of electricity, as it suggests a more constant and steady usage rather than large peaks and troughs.

Mains Electricity

Mains electricity is the general-purpose alternating-current (AC) electric power supply that is delivered to homes and businesses. It is the primary source of electricity for residential and commercial buildings, providing the energy for lighting, heating, cooling, and operating appliances. The characteristics of mains electricity, such as voltage and frequency, vary by country; for instance, it’s typically 230 volts and 50 Hz in many regions.

Master Electrician

A Master Electrician is an advanced level in the electrical trade, representing a high degree of skill, experience, and qualifications. Master electricians have typically completed extensive training and have years of practical experience. They are qualified to plan, design, install, and maintain electrical systems, and often hold leadership roles, supervising other electricians and managing complex projects.

Maximum Demand

Maximum demand refers to the highest level of electrical power demand recorded in a specified period, usually over a month or a year. It is a crucial factor in electrical system design and power supply management, as it determines the capacity requirements for generators, transformers, and transmission lines. Knowing the maximum demand helps in ensuring the electrical infrastructure can handle peak usage without overloading.

Negative Voltage

Negative voltage in an electrical circuit refers to a potential difference where the electric potential is lower at one point compared to another, often designated as the reference or ground. In practical terms, it means the direction of voltage is opposite to the assumed or conventional direction. Negative voltage is common in many electronic circuits and is crucial for operations like signal processing.

NECA (National Electrical and Communications Association)

The National Electrical and Communications Association (NECA) in Australia is a leading industry association for electrical and communications contractors. It provides members with resources and support in areas like safety standards, technical training, and industry advocacy. NECA plays a crucial role in shaping policy, promoting best practices, and ensuring the professional development of its members in the electrical and communications sectors.


An ohm is the unit of electrical resistance in the International System of Units (SI). It is defined as the resistance between two points in a conductor when a constant potential difference of one volt, applied to these points, produces a current of one ampere. This unit is named after Georg Simon Ohm, a German physicist known for his work on electrical resistance.

Ohm’s Law

Ohm’s Law is a fundamental principle in electrical engineering that states the current through a conductor between two points is directly proportional to the voltage across the two points and inversely proportional to the resistance between them. It is typically expressed in the formula I=V/R, where I is the current, V is the voltage, and R is the resistance.

Open Circuit

An open circuit occurs when there is a break in a conducting path, preventing current from flowing. This can be due to an intentional break, like an open switch, or due to a fault, such as a broken wire. In an open circuit, the electrical path is incomplete, and as a result, electrical devices in the circuit will not function.

Parallel Circuit

A parallel circuit is a type of electrical circuit where components are connected across common points or junctions, creating multiple paths for the current to flow. If one component fails in a parallel circuit, current can still flow through the other paths, allowing the remaining components to function. This is in contrast to a series circuit, where all components are in a single path.


In electrical terms, polarity indicates the direction of current flow in a circuit, typically marked by positive (+) and negative (-) symbols. Polarity is crucial for the correct connection of electrical components and systems, as many are sensitive to the direction of current flow. Incorrect polarity can lead to malfunction or damage in electronic devices, making it a key consideration in electrical installations and repairs.

Power Factor

Power factor is a measure of how effectively electrical power is being used. It is defined as the ratio of active power (measured in watts) to apparent power (measured in volt-amperes) in an AC electrical system. A power factor close to 1 indicates efficient use of electrical power, whereas a lower power factor suggests inefficiency, with more apparent power than necessary being used for a given amount of work.

Power Factor Correction

Power factor correction is a technique used to improve the power factor in an electrical system, making it closer to 1. This is typically achieved by adding capacitors or inductors to the circuit, which counteract the effects of inductive or capacitive loads that cause the power factor to deviate from 1. Improving power factor can lead to more efficient energy consumption and reduced demand charges from utility companies.

Reactive Power

Reactive power, measured in volt-amperes reactive (VAR), is the portion of electricity that establishes and sustains the electric and magnetic fields in AC circuits. Unlike active power, reactive power does not perform useful work but is necessary for the functioning of inductive loads like motors and transformers. Managing reactive power is essential for the efficient operation of these systems.


A relay is an electrically operated switch used in electrical circuits. It consists of an electromagnet that, when energised, closes or opens the contacts of a separate circuit. Relays are used for various purposes, including controlling a high-power circuit with a low-power signal, as well as for protection and switching in electrical and electronic systems. 



Reluctance is a measure of the opposition to magnetic flux in a magnetic circuit, analogous to electrical resistance in an electrical circuit. It quantifies how much a material resists the formation of a magnetic field within it. Lower reluctance means easier formation of magnetic fields. This concept is essential in the design of magnetic circuits, such as transformers and electric motors.


Resistance in electrical terms is a measure of the opposition to the flow of electric current in a conductor. It is quantified in ohms (Ω) and depends on the material, length, cross-sectional area, and temperature of the conductor. Resistance determines how much current will flow for a given voltage, according to Ohm’s Law, and is a fundamental concept in designing and analysing electrical circuits.

Resistive Load

A resistive load in an electrical circuit is one where the current and voltage are in phase, meaning there is no phase difference between them. Common examples include incandescent light bulbs and electric heaters. These loads primarily convert electrical energy into heat and have a power factor of 1, as they do not store energy in magnetic or electric fields.

Service Box

A service box, also known as a fuse box or breaker panel, is a key component in a building’s electrical system. It distributes electrical power into subsidiary circuits while providing a protective fuse or circuit breaker for each circuit in a common enclosure. The service box is crucial for managing and protecting the home’s electrical system, acting as the central point where the external power supply is divided and controlled.

Single-Phase Load

A single-phase load refers to an electrical device or system that operates on a single-phase power supply. This type of load is common in residential and light commercial settings. Single-phase loads include most household appliances and lighting fixtures, which are designed to operate on the standard single-phase voltage supplied to homes and small businesses.

Single-Phase Power

Single-phase power is a type of electricity distribution typically used in residential and small commercial applications. It involves a single alternating voltage cycle distributed across two wires, one active and one neutral. This system is sufficient for lower power requirements, powering standard household appliances, lighting, and electronics, and is the most common form of electrical power supply in homes.

Surge Protector

A surge protector is a device designed to protect electrical appliances from voltage spikes. It attempts to limit the voltage supplied to an electric device by either blocking or shorting to ground any unwanted voltages above a safe threshold. Surge protectors are essential for safeguarding sensitive electronics from sudden surges in electrical power, typically caused by lightning strikes or power outages.


A switchboard is an electrical device that distributes electricity from one or more sources of supply to several smaller regions of usage. It is an assembly of panels, each containing switches that allow electricity to be redirected. Switchboards are integral in managing and controlling the flow of electrical power in buildings and are equipped with protective devices for safety and efficiency in power distribution.

Test and Tag

Test and tag is a process of inspecting and testing electrical appliances and equipment for safety according to specific standards. It involves visually inspecting the appliance, testing it with specialised equipment for any electrical faults, and tagging it to indicate compliance with safety standards. This practice is crucial for ensuring electrical safety in workplaces and is often mandated by workplace safety regulations.

Three-Phase Load

A three-phase load is an electrical system or appliance that requires a three-phase power supply for operation. This type of load is common in industrial and commercial settings due to its efficiency in powering heavy machinery and equipment. Three-phase loads benefit from the constant power delivery and improved performance characteristics of three-phase systems, making them suitable for high-power applications.

Three-Phase Power

Three-phase power is a method of electrical power transmission that uses three alternating currents, each phase offset by one-third of the period. This system is more efficient than single-phase power for distributing large amounts of electricity over long distances and for running large motors and heavy loads. It is widely used in industrial and commercial environments due to its ability to provide a constant and balanced power supply.


A transformer is an electrical device that transfers electrical energy between two or more circuits through electromagnetic induction. It is used to increase (step up) or decrease (step down) voltage levels in an electrical circuit. Transformers are essential components in the distribution of electrical power across long distances, allowing for efficient transmission by stepping up voltage for transmission and stepping it down for safe usage in homes and businesses.

Type I

In the context of electrical terminology, “Type I” often refers to a specific category or classification of equipment or standards. The exact meaning can vary depending on the specific application, such as a type of electrical circuit breaker, a category of electrical connector, or a safety classification. It’s important to refer to the relevant industry standards or technical documentation for the specific context in which “Type I” is used.

Utilisation Factor

Utilisation factor is a measure used in electrical engineering to indicate the proportion of time a piece of equipment is actually running at full load compared to the total time it is available for use. This factor is important for assessing the efficiency and capacity utilisation of electrical equipment. A high utilisation factor means the equipment is used more continuously and close to its full capacity.


A volt is the unit of electric potential, potential difference (voltage), and electromotive force in the International System of Units (SI). One volt is defined as the difference in electric potential between two points of a conducting wire when an electric current of one ampere dissipates one watt of power between those points. It is a fundamental unit in the field of electricity and electronics.

Voltage (Volt)

Voltage, also measured in volts, is the electrical potential difference between two points. It is the force that drives electric current through a conductor. In simple terms, voltage can be thought of as the “pressure” that pushes electrical charges through a circuit, and it is a critical factor in the design and operation of electrical systems. Higher voltages can push more current through a conductor, powering larger loads.


A watt is the SI unit of power, equivalent to one joule per second. It quantifies the rate of energy transfer, used in measuring electrical power. A watt is defined by the power produced by a current of one ampere flowing across an electrical potential difference of one volt.

Wattage (Watt)

Wattage refers to the amount of electrical power expressed in watts. It represents the rate at which electrical energy is consumed or produced by a device or system. For example, a light bulb with a wattage of 60 watts uses 60 joules of energy per second. 

240 Volt

240 volts is a standard voltage level for electricity supply in many residential and commercial electrical systems. It’s used for powering larger appliances like ovens, air conditioners, and clothes dryers. This higher voltage allows for more efficient transmission of power with reduced current, leading to less energy loss in wires and enabling more powerful appliances to operate effectively.


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