General Information

Earthing

Earthing is an electrically conductive connection to the electrical potential of the ground. Earthing is a form of ground connection. The neutral potential is not necessarily the earth potential. Ground connection creates a conductive connection to the environment. Earthing or grounding refers to a situation where this environment includes the ground (e.g. steel reinforcement in a concrete floor) or is conductively connected to it. On the one hand there is the live conductor, also referred to as the phase (L), on the other hand the neutral conductor (N) and the protective earth conductor (PE), also referred to as earthing conductor, earthing or earth in short. Together with a residual current device (RCD) or residual current circuit breaker (RCCB), the sole purpose of the earthing conductor is personal protection in relation to electrical wires and systems. Earthing refers to the entirety of all earthing means for the purpose of discharging electrical currents into the foundation earthing.

Grounding

Ground (GND) refers to a conductive body, which is usually assigned zero potential. This represents the reference potential for all signal and operating voltages. In principle, any node of an electrical circuit can serve as ground and be used as reference potential for the specification of all voltages in the respective network. The ground can be potential-free and is in any case connected directly to the protective conductor with the electrical potential of the conductive foundation earthing, as required.
In many case the negative terminal of the power supply also acts as ground. The positive terminal of the power supply and all other voltage and electrical signals of a circuit refer to the neutral (ground) potential. Ground is the common connection for most components.

Protective conductor

In order to be able to establish an effective protective earth conductor system, in addition to the protective conductors and all electronic components all conductive components of a machine must be included in the protective earth conductor system through equipotential bonding.

Note

Installation of electrical systems and components!

When installing electrical systems and components, the protective earth conductors should always be connected first and removed last. The specifications for the protective earth conductor connections depend on the level of leakage currents. The minimum requirement for the protective earth conductor is a KU value¹⁾of 4.5 for leakage currents I_L < 10 mA or KU = 6 for I_L > 10 mA.

¹⁾ The KU-value is a variable for the classification of safety-related types of failure for protection against dangerous shock current and excessive heating. A value of KU = 4.5 in relation to interruption is attained:

▪: with a permanently attached protective conductor ≥ 1.5 mm²

▪: for protective earth conductor connections ≥ 2.5 mm² with plug connectors for industrial systems (IEC 60309−2).

KU = 6 in relation to interruption is attained with permanently connected conductors ≥ 10 mm², wherein the type of connection and routing must comply with the standards applicable to PE conductors.

Measuring leakage currents!

The full cable lengths must be connected for measuring leakage currents. The measurement can take place without load. Further information can be found in section: “Leakage currents”.