Glossary · Electrical engineering and control panels
Protective earth (PE)
Also known as: PE conductor, Protective conductor, Equipment grounding conductor
German: Schutzleiter (PE)
In electrical engineering, the protective earth (PE) conductor is a conductor provided for safety purposes, connecting exposed conductive parts to earth so that a fault current can flow and protective devices can disconnect the supply in time.
- Control panels
In one sentence
The protective earth (PE) conductor connects exposed conductive parts to earth so fault currents trip protective devices in time.
Example
The PE conductor of the incoming supply is connected to the PE terminal next to the main disconnect, from where the protective bonding circuit branches out.
How it applies
- Engineering: The PE conductor is identified by the green-yellow color combination, which must not be used for other conductors. Its cross-section depends on the associated phase conductors. In US terminology, the equipment grounding conductor corresponds to it.
- Maintenance: Interrupting or removing a PE connection can leave parts live in a fault without anyone noticing. Protective conductors must be reconnected and tested after work.
- Documentation: The installation instructions must state how to connect PE and, where relevant, requirements for high leakage currents (for example a second PE conductor). Include explicit warnings against disconnecting PE to solve interference problems.
Protective earth vs. functional earth
PE protects people. Functional earth (FE) serves the function of equipment, for example EMC. Keep them separate in terminology and in circuit diagrams.