ElectricalSystemType
Semantic definition
For certain purposes of electrical regulations, IEC 60364 defines types of system using type identifiers. Assignment of identifiers depends upon the relationship of the source, and of exposed conductive parts of the installation, to Ground (Earth). Identifiers that may be assigned through IEC 60364 are:
•TN type system, a system having one or more points of the source of energy directly earthed, the exposed conductive parts of the installation being connected to that point by protective conductors, •TN C type system, a TN type system in which neutral and protective functions are combined in a single conductor throughout the system, •TN S type system, a TN type system having separate neutral and protective conductors throughout the system, •TN C S type system, a TN type system in which neutral and protective functions are combined in a single conductor in part of the system, •TT type system, a system having one point of the source of energy directly earthed, the exposed conductive parts of the installation being connected to earth electrodes electrically independent of the earth electrodes of the source, •IT type system, a system having no direct connection between live parts and Earth, the exposed conductive parts of the electrical installation being earthed.