Definitions
Wiring System: An assembly made up of cables or busbars and the parts that secure, and if necessary enclose, the cables or busbars.
DSO: The distribution system operator.
Main Supply Point ( origin of an installation ): The point at which the supply is connected to an installation.
Nominal Voltage: A voltage by which an installation, or part of an installation, is designated.
Low Voltage: A nominal voltage exceeding 50 V AC or 120 V DC but not exceeding 1000 V AC or 1500 V DC.
Extra Low Voltage: A nominal voltage not exceeding 50 V AC or 120 V DC between conductors or between a conductor and earth.
Isolation ( isolating function ): Function intended to cut off the supply from all or a discrete section of the installation by separating the installation or section from every source of electrical energy for reasons of safety.
Isolating Switch: A mechanical switching device that, in the open position, complies with the requirements specified for the isolating function.
Main Isolating Switch: A switching device provided at the main supply point for the purpose of isolating an installation.
Switchgear: Equipment provided to be connected to an electrical circuit for the purpose of carrying out one or more of the following functions: protection, control, isolation, switching.
Distribution Board: An assembly of protective devices, including two or more fuses or circuit breakers, arranged for the distribution of electrical energy to final circuits or to other distribution boards.
Circuit: Part of an electrical installation supplied from the same origin and protected against overcurrents by a single protective device.
Current Using Equipment: Equipment intended to convert electrical energy into another form of energy, for example light, heat or motive power.
Final Circuit: A circuit connected directly to current using equipment or to socket outlets.
Point ( in wiring ): A termination of the fixed wiring intended for the connection of current- using equipment.
Luminaire: Apparatus that distributes, filters or transforms the light transmitted from one or more lamps and includes all the parts necessary for supporting, fixing and protecting the lamps and where necessary, circuit auxiliaries together with the means for connecting them to the supply. It does not include the lamps themselves.
Main Earthing Terminal ( MET ) or Bar: A terminal or bar provided for the connection of protective conductors, main equipotential bonding conductors and conductors for functional earthing if any, to the means of earthing.
Live Part: A conductor or conductive part intended to be energised in normal use, including a neutral conductor, but not a PEN conductor.