Electrical Terminology
Here are some electrical terms that are relevant to consumers with a focus on terms that would be beneficial to understand.
These terms should provide a good base of understanding for consumers. Some of these terms are used in the context of specific safety measures and it’s important that consumers know the purpose of these devices in keeping their homes and businesses safe.
A
Appliance
A device that uses electricity to perform a function.
B
Bonding
Connecting different metallic parts of a building to the earthing system to minimize the risk of electric shock and touch voltages during faults.
C
Circuit Breaker
A device that automatically stops the flow of electricity (current) in a circuit if there is a fault, such as an overload. This helps to prevent fires and electric shocks.
Consumer Unit
This is a main control panel, sometimes called a fuse box, that distributes electricity around a building. It contains circuit breakers or fuses. A consumer unit may have a plastic or metal enclosure. Protective devices are located here in case a circuit trips.
D
Distribution Board
A point of distribution of electricity (see Consumer Unit).
Distribution Network Operator (DNO)
A party that distributes electricity to consumers.
E
Earth Fault Loop Impedance
The resistance of the path an electrical fault will take to the earth, which must be low enough to allow protective devices to operate quickly.
Earthing
A way of connecting electrical equipment to the earth, providing a safe path for electricity in the event of a fault. This helps to prevent electric shocks.
Electrical Installation Certificate (EIC)
A certificate confirming that new electrical work has been done safely and meets required standards.
Electrical Installation Condition Report (EICR)
A report on the safety of an electrical system.
ELV (Extra-Low Voltage)
A low voltage electrical system, often used for lighting, that reduces the risk of electric shock.
F
G
H
Harmonic Currents
Distortions in the electrical current, which can cause problems in electrical systems.
I
IP Code
A rating system that indicates how well an enclosure protects against dust and water.
Isolator/Isolating Switch
A switch that is used to completely disconnect the electrical supply, to allow for safe work.
J
K
L
Luminaire
A complete light fitting, including the bulb and any parts needed to support, fix, and protect it.
M
Main Switch
The main switch in a consumer unit which allows the entire electrical supply to be turned off.
Meter Operator (MO) or Distribution Service Operator (DSO)
A party that provides and charges for electricity to consumers.
N
O
Overcurrent
When an electrical circuit carries more current than it is designed for, which can cause overheating and damage.
Overload
A type of overcurrent where too much current flows in a circuit, often from too many appliances being connected.
P
Prospective Fault Current
The maximum electrical current that could flow in a fault condition
Protective Conductor
A wire that provides a safe path for electrical current in the event of a fault.
Q
R
RCD (Residual Current Device)
A safety device that quickly switches off electricity when it detects that current is flowing to earth, reducing the risk of electric shock.
S
SELV (Separated Extra-Low Voltage)
An extra-low voltage system with additional safety measures that provides a higher degree of protection against electric shock.
Surge Protective Device (SPD)
An electric device typically installed in distribution boards, communications systems, extension cords etc., for the purpose of protecting against electrical surges and spikes, including those caused by lightning or motors like washing machines and fans. These devices are installed in residential consumer units, to protect equipment in a household from similar hazards.
T
U
V
Voltage Drop
A reduction in electrical voltage along a cable.
W
Wiring Accessories
Items such as sockets, switches and light fittings.
Wiring Regulations (BS 7671)
The national standard for electrical installations.
Wiring System
The complete network of cables, conduits, and other components that carry electricity within a building.