What Is a Protective Earthing Conductor?

Protective earthing conductor (identification: PE) or (protective grounding conductor, US): protective conductor provided for protective earthing [defined in the IEC 60050-195-2021]. In other words, it is a protective conductor designed to implement the earthing performed for the purpose of electrical safety.

What Are Protective Earthing Conductors?

In order to protect people and animals from electric shocks in electrical installations of buildings, protective earthing is carried out, which provides for the electrical connection of exposed conductive parts of Class I electrical equipment with the protective conductors of the electrical installation of the building in accordance with the features of the type of system earthing.

In the TN-C, TN-S and TN-C-S types of system earthing, the exposed conductive parts of Class I electrical equipment are electrically connected to the earthed live parts of the power supply. With the TT and IT types of system earthing, the exposed conductive parts of Class I electrical equipment are connected to the earthing arrangement of the electrical installation of the building. The protective conductors in the electrical installations of buildings corresponding to the types of system earthing listed are protective earthing conductors.

It follows that protective earthing conductors must comply with the requirements of the regulations for protective conductors.

To illustrate an example, see Figure 1 where you can see the location of the protective earthing conductors:

Example of part of a circuit with a protective earthing conductor
Figure 1. Example of part of a circuit with a protective earthing conductor (based on figure B.54.1 of IEC 60364-5-54-2011)

Figure 1 (see “https://www.asutpp.com/protective-conductor-pe.html – Figure 3″ for a complete picture) shows the following:

  • 1 – Protective earthing conductor (PE);
  • DB – Distribution board;
  • MDB – Main distribution board;
  • MET – Main earthing terminal.

In the electrical installations of buildings, protective conductors may be used which must not have an electrical connection to the earthing arrangement. For example, protective conductors connecting the exposed conductive parts of Class I equipment connected to the secondary winding of an isolating transformer, protective bonding conductors used to perform local equipotential bonding, and some other protective conductors. These protective conductors are not protective earth conductors.

Color and Alphanumeric Identification Requirements

Protective earthing conductors shall be identified by the bi-colour combination GREEN-AND-YELLOW according to IEC 60445-2021.

The colour combination GREEN-AND-YELLOW shall be such that, on any 15 mm length of the conductor where colour coding is applied , one of these colours covers at least 30 % and not more than 70 % of the surface of the conductor, the other colour covering the remainder of that surface.

If bare conductors used as protective conductors are provided with colouring they shall be coloured GREEN-AND-YELLOW, either throughout the whole length of each conductor or in each compartment or unit or at each accessible position. If adhesive tape is used, only bi-coloured GREEN-AND-YELLOW tape shall be applied.

If extraneous-conductive-parts are used as a protective conductor, identification by colours is not necessary.

The alphanumeric identification of a protective earthing conductor shall be “PE”.

References

  • IEC 60050-195-2021
  • IEC 60364-5-54-2011
  • IEC 60445-2021