Electrical Conductor (Within Electrical Distribution System)

In this article, we will look at a basic term in low-voltage electrical installations, namely the term “electrical conductor” or “conductor”. This term is constantly confused with the word “wire”, for example. But a wire is only one kind of conductor.

What Is an Electrical Conductor?

Electrical conductor is a conductive part intended to carry a specified electric current [this term is defined in the IEC 60050-195-2021]. In another part of the International Electrotechnical Vocabulary, IEC 60050-826, the term in question is defined similarly.

Note 1 – The term “conductor” is often used for an element the length of which is large with respect to the cross-sectional dimensions, e.g. conductors of a line or of a cable.

Note 2 – The English term “conductor” and the French term “conducteur” have also the meaning of “conducting medium”.

Note 3 – In French, the term “conducteur” is also used as an adjective corresponding to the English “conductive”.

In IEC standards and other documents, the term in question is mainly defined in relation to wires and cables for various purposes. For example, IEC 62219 and IEC 62420 define the term “conductor” in the sense of “wire” as follows:

material intended to be used for carrying electric current consisting of a plurality of uninsulated wires twisted together.

IEC 62219

In the IEC 61328 technical specification and the IEC 61911 technical report, the terms “conductor”, “cable” and “wire” have the same definition:

bare or insulated wire or combination of wires, suitable for carrying an electric current.

IEC 61328

The term “conductor” is used in regulatory and legal documentation to distinguish from the variety of conductive parts those that are originally designed to conduct electrical current in any electrical circuits of electrical installations or electrical equipment. In addition to the qualitative characteristic of the conductor, indicating its ability to conduct electric current, each conductor has a quantitative characteristic – the value of the electric current that it can conduct for a long time under normal conditions. The latter characteristic is called the continuous current-carrying capacity of a conductor (less commonly referred to as the rated current of a conductor).

Examples of Electrical Conductors

Conductors primarily include the conductors of wires and cables used for fixed wiring in the electrical installation of a building, the conductors of flexible wires and cables used to connect portable and mobile electrical equipment to fixed wiring, various busbars used in low-voltage switchgear and bus ducts, and other conductive parts that perform the function of a conductor.

Cable core example conductor
The cable cores are an example of a conductor

Types of conductors in electrical installations of buildings.

Various types of conductors are used in electrical installations in buildings. To provide electrical equipment with electrical energy, AC circuits use:

To provide electrical equipment with electrical energy in DC electrical circuits, the following are used:

Protective conductors, including protective earthing conductors and protective bonding conductors, as well as PEN, PEM, and PEL conductors, are used in electrical installations of buildings to protect humans and animals from electric shock.

The earthed line conductors (LE) are used in single-phase 2-wire AC electrical systems, in three-phase 3-wire AC electrical systems without the neutral and in 2-wire DC electrical systems.

Under normal conditions, the line conductors, the neutral conductor, and the mid-point conductor are energized. Therefore, they are live conductors.

PEN, PEM, and PEL conductors are not considered to be live conductors. However, under normal conditions, PEN-, PEM- and PEL-conductors conduct electric currents in the same way as line, neutral and mid conductors. Therefore, the listed conductors are current-carrying conductors that are considered when specifying the total number of conductors in an electrical circuit, network, or system. PE protective conductors are not designed to conduct electric currents under normal conditions. They are not specified in the total number of conductors.

In every installation a main earthing terminal shall be provided to connect the following to the earthing conductor:

IEC 60364-1, clause 312.1 “Current-carrying conductors depending on kind of current” classifies current-carrying conductors used in AC and DC electrical circuits of low-voltage electrical installations. The conductor arrangements described in this clause are not exhaustive. They are included as examples of typical arrangements. It is recommended to report other arrangements to the IEC.

References

  • IEC 60050-195-2021
  • BS7671