Earth conductor (PE: Protected Earth)

The protective earth conductor – also known as the PE conductor (protective earth) – is an indispensable component of modern electrical installations. It is used for personal protection and the safety of electrical devices by preventing dangerous contact voltages and safely conducting the current to earth in the event of a fault.

What is a protective conductor?

The protective earth conductor is an electrically conductive conductor that is connected to the earthing system of an electrical installation. It does not carry any operating current, but only becomes active in the event of a fault. Its main task is to divert the current safely to earth in the event of an insulation fault, thereby preventing life-threatening voltages on accessible housing parts.

Protective conductor in connection with transformers

Transformers are central components in power distribution. The protective conductor also plays an important role here:

Earthing the transformer: The protective conductor is connected to the housing and, if necessary, to the star point of the transformer to ensure safe earthing.

Residual current discharge: In the event of a fault, e.g. due to damaged insulation, the protective conductor conducts the current directly to earth and enables fuses or residual current circuit breakers to be tripped.

Equipotential bonding: The protective conductor ensures uniform earth potential equalization between different parts of the system and prevents voltage differences.

Labeling and standards

In Europe, the protective earth conductor is marked green-yellow in accordance with DIN VDE 0100 and international standards. It must not be used as a neutral conductor or external conductor. In protective contact sockets, the protective conductor is connected directly to the earthing contact.

Why is the protective conductor important?

Personal protection: Prevents electrical accidents caused by touching live housing parts.

Fire protection: Diverts fault currents and prevents overheating or arcing.

Standard-compliant installation: a prerequisite for the approval and safe operation of electrical systems and devices.