Electrical distribution network: low-voltage electrical network consisting of the power source and a distribution line (overhead line or underground cable) and intended for supplying of the electric power to electrical installations of buildings and other low-voltage electrical installations [defined in the IEC TS 62257-5:2015, B.1.2].
Note. The word “electrical” is often not used when talking about distribution network.
Figure 1 below illustrates the connection of a building’s electrical installation to the low-voltage distribution network.
The term “(electrical) distribution network” should not be confused with the term “(electrical) distribution circuit”. The term “distribution network” should be used in the normative documentation to identify the set of low-voltage electric power installations to which the electrical installations of buildings are connected, and the term “distribution circuit” – to identify those parts of the electrical installations of buildings, which are used to provide electric power to its low-voltage switchgear.
The technical measures carried out in the low-voltage distribution network influence the level of electrical safety in the electrical installations of buildings connected to it. Therefore, measures to protect people from electric shocks in the electrical installations of buildings must be linked to the requirements to be met by the distribution network.
The type of system earthing is the main characteristic that can be used to harmonize the starting points used in electrical safety requirements for two heterogeneous objects – the low-voltage distribution network and the electrical installation of the building, which are part of one set, which is the low-voltage distribution system.