Siemens SIMATIC S7-1500 System Manual page 88

Dimension the protective conductor as follows:
Table 6- 3
Cross-section of mains supply
conductor
≤ 16 mm²
> 16 mm² to ≤ 35 mm²
> 35 mm²
For other materials, the cross-section of the protective conductor is to be increased so that it
has at least the same conductance as copper.
SIMATIC Drive Controller
System Manual, 11/2019, A5E46600094-AA
6.9 Protective conductor and potential equalization, functional ground
Cable cross-section for copper protective conductor
Cross-section of protective conductor
As mains supply conductor cross-section
16 mm²
0.5 × mains supply conductor cross-section
Connecting
87