Glossary A-Z

Electrical current that reverses direction at a certain frequency – in Australia at a nominal frequency of 50 Hz - standard mains electricity supply.

The conductor that carries electrical current from the supply to the appliance or equipment. For appliances, typically brown in colour in Australia. Contact presents an electric shock hazard.

The measure of flow of electrical current through a circuit, showing how much electricity is moving at any moment. Electrical current is measured in amps (A).

Electrical current can be understood as the flow rate of electricity, similar to the volume of water flowing past a point in a river - where a larger current is like a wider or fuller river carrying more water each second.

Voltage is like the slope or height difference driving the river — it provides the push.

Resistance is like rocks, bends, or narrow sections that restrict flow.

High current means a large volume of flow, which is why it causes heating, just as a strong river has more erosive force.

Power is like the total energy of the river in action — determined by both how steep the slope is and how much water is flowing — representing how much work the river can do, such as turning a waterwheel or causing erosion.

Any electrical device connected to a power source, including portable, fixed, or stationary equipment.

A classification system defining the construction and method of protection against electric shock (Class I, Class II, Class III).

A test instrument used for the inspection and testing of equipment accordance with AS/NZS 3760.

The inspection and testing of electrical equipment to ensure it is electrically safe for use. In Australia this is predominantly performed to AS3760.

Apparent power is calculated by multiplying volts by amps (V × A) and represents the total electrical power supplied to a device. It is measured in volt-amps (VA) and is commonly used to rate equipment such as generators, power supplies, and UPS systems.

A dangerous release of energy caused by a serious electrical fault, producing intense heat, light, and pressure.

A person permitted under workplace procedures or legislation to perform specific electrical tasks.

A 4mm connector used general electrical test instrument terminals which may be sheathed or unsheathed.

The electrical connection of exposed conductive parts to the protective earth.

The verification of a test instrument to ensure measurements are within specified tolerances. Sometimes includes adjustment depending on the service offered and instrument limitations.

A classification defining the transient overvoltage levels an electrical test instrument can safely withstand (CAT I–IV) in accordance with ISO 601010.

The conductive structural framework of an appliance that may require protective earthing.

Electrical equipment with basic insulation relying on a protective earth connection for safety.

Class 1 is the name of a test sequence commonly installed in Metrel 3309 Appliance Testers by some distributors. The test is suited to earthed equipment and includes an earth continuity test and an insulation resistance test.

Class 1 Leakage is the name of a test sequence commonly installed in Metrel 3309 Appliance Testers by some distributors. The test is suited to earthed equipment and includes an earth continuity test and a current leakage test using the differential method.

Dbl Ins Leakage is the name of a test sequence commonly installed in Metrel 3309 Appliance Testers by some distributors. The test is suited to double insulated equipment and includes a touch leakage test with measurement to the applied probe.

Class 2 is the name of a test sequence commonly installed in Metrel 3309 Appliance Testers by some distributors. The test is suited to double insulated equipment and includes an insulation resistance test with measurement to the applied probe.

Equipment protected by double or reinforced insulation and not reliant on protective earthing.

Equipment supplied from a separated extra-low voltage (SELV) source only.

A three-pin IEC appliance connector commonly used on laptop power supplies.

A person who has acquired the necessary knowledge and skills through training or experience to carry out inspection and testing safely. A full definition of the expectations of competency is listed in AS3760..

A material or wire that allows electrical current to flow.

An electrically controlled switching device used to make or break power circuits.

The existence of a complete, unbroken electrical path allowing current to flow between two points.

Dbl Ins Std is the name of a test sequence commonly installed in Metrel 3309 Appliance Testers by Test and Tag Supplies. The test is suited to double insulated equipment and includes an insulation resistance test with measurement to the applied probe.

Dbl Ins Leakage is the name of a test sequence commonly installed in Metrel 3309 Appliance Testers by Test and Tag Supplies. The test is suited to double insulated equipment and includes a touch leakage test with measurement to the applied probe.

An electrical current that flows in one direction only.

Electrical equipment that has been isolated from all sources of an electrical supply.

Leakage current measured as the difference between current flowing in active and neutral conductors.

A method of protection against electric shock using basic and supplementary insulation.

A conductor that connects exposed conductive parts of electrical equipment to the installation earthing system.

A test measuring the resistance of the protective earth connection using a higher test current.

A low-current test used to confirm that the protective earth connection is intact.

Earthed App Std is the name of a test sequence commonly installed in Metrel 3309 Appliance Testers by Test and Tag Supplies. The test is suited to earthed equipment and includes an earth continuity test and an insulation resistance test.

Earthed App Lkg is the name of a test sequence commonly installed in Metrel 3309 Appliance Testers by Test and Tag Supplies. The test is suited to earthed equipment and includes an earth continuity test and a current leakage test using the differential method..

Any device, appliance, cable, fitting, or apparatus that uses or conducts electricity.

Any condition that may result in electric shock, fire, or equipment damage.

An earthed appliance where earth connections are enclosed in non-conductive parts. Common examples includes appliances such as coffee machines and high power jet washers. In these examples the equipment is earthed equipment but there is no access to the protectively earthed conductive surfaces.

AS3760 has provision for these types of appliances allowing a visual inspection or an insulation resistance test or current leakage test only.

EPOD is and acronym for Electrical Portable Outlet Device. This is a portable power distribution unit, such as a power board or extension outlet, designed to provide multiple socket outlets from a single electrical supply.

Ext Lead Lkg Lead is the name of a test sequence commonly installed in Metrel 3309 Appliance Testers by Test and Tag Supplies. The test is suited to extension leads where power is required to be applied to the lead to facilitate the leakage test. It includes an earth continuity test, a current leakage test and and a polarity test.

Current flowing as a result of an electrical fault.

The supporting structural component of equipment, which may require earthing if conductive.

An earth connection used to help equipment operate correctly, not for safety.

A device used to secure and protect cables entering equipment enclosures.

A standard electrical power outlet providing power via a plug.

A voltage or current waveform distortion occurring at multiples of the fundamental frequency.

Equipment designed for hostile environments under AS/NZS 3012, capable of withstanding mechanical stress, moisture, and rough handling.

An environment where equipment is exposed to conditions increasing risk of damage. For example where the electrical appliances are in environments likely to result in damage including influencing factors such as chemicals, heat, mechanical damage, moisture or vibration.

IEC/Ext Lead is the name of a test sequence commonly installed in Metrel 3309 Appliance Testers by Test and Tag Supplies. The test is suited to extension leads and includes an earth continuity test, an insulation resistance test and and a polarity test.

IEC/Lead/EPOD is the name of a test sequence commonly installed in Metrel 3309 Appliance Testers by some test instrument suppliers. The test is suited to extension leads and EPODS and includes an earth continuity test, an insulation resistance test and and a polarity test.

An international standards body governing electrical technologies.

A two-pin IEC appliance inlet commonly used for low-power Class II devices.

Standard IEC connectors used for computers and office equipment.

A commonly used term for an RCD test that verifies correct operation by intentionally creating a controlled imbalance between active and neutral conductors to simulate an earth leakage fault. While often referred to as an “inject” test, the process does not involve injecting current into the RCD; instead, the device is operated by producing the residual current it is designed to detect.

A brief, high surge of current when equipment is first switched on.

The resistance between live parts and earth indicating insulation effectiveness.

The separation of equipment from all sources of electrical energy.

A transformer providing electrical separation between supply and load. Commonly isolation transformers are used to enable portable RCD's to be tested avoiding tripping upstream (switchboard) RCD's.

A generator with electrically separated windings not connected to earth.

An isolated winding generator provides protection by preventing a single fault from creating a dangerous earth return path, but AS/NZS 3012 limits the number of earthed appliances that may be connected because multiple connected appliances increase the risk that a second, simultaneous fault could complete a circuit to earth and create a hazardous situation.

The measured residual current, representing the imbalance between active and neutral conductors. In RCD testing, ΔI is used to indicate the leakage current level that causes the device to operate.

Kyoritsu is a leading high quality test instrument manufacturer based in Japan.

An unintended current flow to earth caused by an insulation fault.

The total impedance of the earth fault loop, including the active conductor, protective earth conductor, and supply transformer. Zs is measured to verify that sufficient fault current will flow to operate protective devices within the required disconnection time.

A rechargeable battery chemistry commonly used in portable electronic devices.

Megger is a UK-based manufacturer of electrical test and measurement equipment that operates globally through regional offices and subsidiaries.

A connection between neutral and earth at the main switchboard in Australian installation earthing systems.

Metrel is a European manufacturer of electrical test and measurement equipment headquartered in Slovenia, supplying portable testing and safety instruments worldwide.

The normal electricity supply provided to premises.

The conductor that provides the return path for electrical current.

A rechargeable battery chemistry used in portable equipment.

The unit of measurement for electrical resistance.

Ohm’s Law states that the current through a conductor is directly proportional to the voltage applied and inversely proportional to the resistance, expressed as V=I×RV = I \times RV=I×R. Ohm’s Law is fundamental to understanding how voltage, current, and resistance interact in an electrical circuit.

Current exceeding safe operating limits.

A test instrument used in accordance with AS/NZS 3760.

The definition given to a person or organisation responsible for workplace health and safety under the harmonised workplace health and safety regulation.

This legal term used in Australian work health and safety (WHS legislation to define who holds primary responsibility for ensuring health and safety in the workplace. The term is intentionally broad and applies to a wide range of entities, including companies, sole traders, partnerships, government bodies, associations, and not-for-profit organisations. It focuses on the activity being carried out rather than the legal structure of the organisation.

The PCBU concept is used in all Australian states and territories that have adopted the model WHS laws, which were developed to harmonise safety legislation nationwide. These jurisdictions include Queensland, New South Wales, South Australia, Tasmania, Western Australia, the Northern Territory, and the Australian Capital Territory. In these states and territories, PCBUs have

The protective earth conductor used to connect exposed conductive parts of electrical equipment to earth. The PE conductor provides a low-resistance path for fault current to flow, allowing protective devices to operate and reduce the risk of electric shock.

Protective clothing and equipment worn to reduce exposure to hazards.

Electrical equipment that can be readily moved while connected to supply.

The rate at which electrical energy is transferred or consumed in a circuit, calculated as volts multiplied by current ( P=V×IP = V \times IP=V×I ) and measured in watts.

PrimeTest is a branded series of portable appliance testers marketed by Seaward.

The Sunshine State

A ramp test is used to check the operating sensitivity of an RCD by gradually increasing the simulated earth leakage current until the device trips. Instead of applying a sudden fixed fault current, the test instrument slowly creates an increasing imbalance between active and neutral, forming a “ramp” of residual current.

The current level at which the RCD operates is recorded and compared to its rated trip value, typically 30 mA. A correctly functioning RCD should trip within a specified range around its rating, confirming that it will respond appropriately to real leakage faults. Unlike a trip-time test, a ramp test focuses on the amount of current required to cause tripping, making it useful for assessing RCD condition and sensitivity.

An electrically operated switch used to control circuits.

The imbalance between current in active and neutral conductors.

A safety device that disconnects supply when leakage current is detected.

Opposition to the flow of electrical current, measured in ohm.

Voltage is like the slope or height difference driving the river — it provides the push.

Resistance is like rocks, bends, or narrow sections that restrict flow.

High current means a large volume of flow, which is why it causes heating, just as a strong river has more erosive force.

Power is like the total energy of the river in action — determined by both how steep the slope is and how much water is flowing — representing how much work the river can do, such as turning a waterwheel or causing erosion

The resistance of the protective earth conductor between exposed conductive parts and the earth point, typically measured during continuity or earth bond testing to verify the integrity of the earth connection.

The resistance between live conductors and earth, or between live conductors, indicating the effectiveness of insulation. Insulation resistance is measured by applying a DC test voltage (commonly 250 V or 500 V) and is expressed in megaohms (MΩ).

Another term for an RCD.

SafeTcheck was an appliance tester manufactured by Trisan on behalf of Trio Electrix and Trio Smartcal.

Seaward is a leading Appliance Tester manufacturer based in the UK. Seaward is owned by Metrawatt International GmbH, as part of the GMC-Instruments Group. A German test instrument manufacturer.

The standard waveform of alternating current.

A single-phase electrical supply uses one alternating current delivered via an active (live) conductor and a neutral, with an earth for safety, and is commonly used for general-purpose power and lighting where low power demand is required.

Most domestic and the majority of commercial electricity supply is single phase..

Electrical equipment requiring specific controls under legislation.

The stationary part of a generator containing the windings.

A component preventing stress on electrical cables.

An unsafe lead with plugs at both ends.

An assembly containing switching and protection equipment.

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A power supply using high-frequency switching

A label showing inspection and test status under AS/NZS 3760.

The process of inspecting, testing, and tagging equipment.

A trip time test is used to verify that a residual current device (RCD) operates within the required time limits when subjected to a specified earth leakage current, ensuring the device will disconnect the supply quickly enough to reduce the risk of electric shock.

During a trip time test, the test instrument (RCD tester or Appliance Tester) creates a controlled imbalance between the active and neutral conductors, producing a residual current equal to the RCD’s rated sensitivity (commonly 30 mA, or a multiple such as 1× or 5× rated current). The moment the test current is applied, the instrument measures the time taken for the RCD to trip and disconnect the circuit.

The measured trip time is then compared against the maximum allowable limits set by the relevant standard. For example, a 30 mA general-purpose RCD must trip within 300 milliseconds under AS3760. This ensures that under real fault conditions, dangerous touch voltages are removed quickly enough to protect people from serious injury.

Unlike a ramp test, which determines the current level required to cause tripping, a trip time test focuses on how quickly the RCD operates once a fault current is present. Together, these tests confirm both the sensitivity and speed of the RCD, providing confidence that it will perform its protective function correctly.

Electrical current that may flow through accessible conductive parts.

A three-phase electrical supply uses three alternating currents offset from each other to deliver power more efficiently and consistently than single-phase supply, which uses only one alternating current.

Three-phase supplies typically consist of five conductors: one earth, three active (live) conductors, and one neutral. Some three-phase systems do not include a neutral; in these cases, the load must be evenly balanced across all three phases.

Analogy:
A single-phase supply is like a single-cylinder engine where power is delivered in distinct strokes, while a three-phase supply is like a three-cylinder engine where power delivery overlaps, providing more consistent output.

A device transferring electrical energy via electromagnetic induction. Commonly found in electrical appliances and electronics.

A short-duration voltage or current spike.

Trisan is an Australian-based supplier and manufacturer of electrical testing equipment, focused on test and tag applications. Trisan are based in Adelaide, South Australia.

The time taken for a Residual Current Device (RCD) to disconnect the supply after a fault current is applied. Δt is measured during RCD time testing to confirm compliance with required trip times.

The test voltage applied by an electrical test instrument during a measurement, such as insulation resistance or continuity testing. Commonly indicates the actual voltage present at the test terminals, confirming that the correct test voltage is being applied and that the circuit under test is not energised.

A condition where the electrical current flowing in a circuit or appliance is below its normal or expected operating level. Under current may indicate reduced supply voltage, increased circuit impedance, poor connections, mechanical load issues, or internal equipment faults, and can result in improper operation or reduced performance.

The electrical force that drives current through a circuit.

Voltage is like the slope or height difference driving the river — it provides the push.

Resistance is like rocks, bends, or narrow sections that restrict flow.

High current means a large volume of flow, which is why it causes heating, just as a strong river has more erosive force.

Power is like the total energy of the river in action — determined by both how steep the slope is and how much water is flowing — representing how much work the river can do, such as turning a waterwheel or causing erosion

A measure of electrical energy use or production, measured in watts.

The total impedance of the earth fault loop, including the active conductor, protective earth conductor, and supply transformer. Zs is measured to verify that sufficient fault current will flow to operate protective devices within the required disconnection time.