Glossary of Electrical Terms

This glossary aims to provide clear definitions of key electrical terms, focusing on concepts relevant to New Zealand electrical regulations and electrical theory.

A

  • Ampere (A) – The unit of electrical current. One ampere equals one coulomb of charge passing a point per second.
  • AS/NZS 3000 (Wiring Rules) – The standard governing electrical installations in Australia and New Zealand.
  • AS/NZS 5033 – The standard for photovoltaic (solar) system installations in NZ.
  • AS/NZS 4777 – The standard covering grid-connected inverter systems in NZ.
  • Alternating Current (AC) – Electric current that reverses direction periodically, used in mains electricity.
  • Active Conductor – A conductor that carries current under normal operation (e.g., phase wire in AC circuits).

B

  • Bi-Metallic Strip – A strip made of two metals with different expansion rates, used in thermal switches and circuit breakers.
  • Breakdown Voltage – The voltage at which an insulating material fails and allows current to pass.
  • Busbar – A conductive bar used for high-current power distribution.

C

  • Circuit Breaker – A protective device that automatically disconnects a circuit during a fault.
  • Conduit – A tube for protecting electrical wiring.
  • Capacitor – A component that stores electrical energy in an electric field.
  • Certificate of Compliance (CoC) – A document certifying that an electrical installation meets NZ regulations.
  • Current (I) – The flow of electric charge in a circuit, measured in amperes (A).
  • Conductor – A material that lets electricity flow easily, like copper or aluminum. It’s used in wires to carry electricity.
  • Consumer Mains – The cable connecting a property to the electricity supply network.

D

  • Direct Current (DC) – Electrical current that flows in one direction only.
  • Distribution Board (DB) – A panel containing circuit breakers or fuses that distribute electrical power.
  • Double Insulation – A safety feature where electrical devices have two layers of insulation, eliminating the need for an earth connection.

E

  • Earth (Ground) – A connection to the earth that provides a path for fault currents and improves safety.
  • Earth Leakage Circuit Breaker (ELCB) – A device that trips when current leaks to earth, preventing electric shocks.
  • Electrical Resistance (R) – The opposition to current flow, measured in ohms (Ω).
  • Electromagnetic Interference (EMI) – Unwanted electrical noise affecting electronic devices.

F

  • Fault Current – The abnormal current that flows during a short circuit or insulation failure.
  • Fuse – A protective device that melts when excessive current flows, breaking the circuit.
  • Frequency (Hz) – The number of AC cycles per second, measured in hertz (Hz). NZ operates at 50Hz.

G

  • GFCI (Ground Fault Circuit Interrupter) – Also known as an RCD (Residual Current Device), it prevents electric shocks by detecting leakage currents.
  • Grid-Tied System – A solar power system connected to the electricity grid.

H

  • Harmonics – Distorted electrical waveforms that can cause overheating and inefficiencies in electrical systems.

I

  • Insulation Resistance – The resistance of an insulating material, ensuring no unwanted current leakage.
  • Insulator – A material that blocks electricity, like rubber or plastic. It’s used to keep electricity safely contained.
  • Inverter – A device that converts DC (e.g., from solar panels) to AC for use in homes and the grid.
  • Impedance (Z) – The combination of resistance and reactance in an AC circuit, measured in ohms (Ω).

J

  • Joule (J) – A unit of energy; one joule equals one watt-second.

K

  • Kilowatt (kW) – A unit of power equal to 1,000 watts.
  • Kilowatt-hour (kWh) – A unit of energy; the amount of energy used by a 1 kW appliance running for one hour.

L

  • Live Conductor – Any conductor that carries voltage in normal operation.
  • Load – The total power demand placed on an electrical system.
  • Low Voltage (LV) – In NZ, low voltage refers to voltages up to 1,000V AC or 1,500V DC (as per AS/NZS 3000).

M

  • Megger Test – A test using a megohmmeter to measure insulation resistance.
  • Main Switch – The switch that controls power to an entire installation.

N

  • Neutral (N) – A conductor that completes the electrical circuit back to the supply.
  • Nominal Voltage – The standard voltage level of an electrical system (e.g., 230V AC in NZ).

O

  • Ohm (Ω) – The unit of electrical resistance.
  • Ohm’s Law – A formula that describes the relationship between voltage, current, and resistance in an electrical circuit:

P

  • Photovoltaic (PV) – The technology used in solar panels to convert sunlight into electricity.
  • Protective Earth (PE) – A conductor used for safety to prevent electric shocks.
  • Power Factor (PF) – The efficiency of an AC electrical system, ranging from 0 to 1.

Q

  • Qualified Electrical Worker (QE) – A licensed professional authorized to perform electrical work in NZ.

R

  • RCD (Residual Current Device) – A safety device that disconnects power when it detects leakage current.
  • Resistance (R) – The opposition to current flow, measured in ohms (Ω).

S

  • Short Circuit – A fault where current bypasses the normal load, leading to high current flow.
  • Stand-Alone Power System (SAPS) – An off-grid power system using renewable energy and batteries.
  • Switchboard – A panel that distributes electricity to different circuits.

T

  • Transformer – A device that changes voltage levels in an AC system.
  • Thermal Overload Protection – A feature in circuit breakers that trips when excessive heat is detected.

U

  • Uninterruptible Power Supply (UPS) – A backup power system providing short-term electricity during outages.

V

  • Volt (V) – The unit of electrical potential.
  • Volt Drop – The reduction in voltage along a conductor due to resistance.

W

  • Watt (W) – The unit of power; 1 watt = 1 joule per second.
  • Wiring Rules – The electrical safety standards specified in AS/NZS 3000.

X, Y, Z

  • X/R Ratio – The reactance-to-resistance ratio used in short-circuit calculations.
  • Zero Sequence Current – A type of fault current in three-phase systems.

This glossary will be continuously updated to include more terms relevant to NZ electrical regulations and electrical theory.