Siemens SIMATIC ET 200SP Operating Instructions Manual page 21

Rule 5: Homogeneous reference potential
● Create a homogeneous reference potential and ground all electrical equipment.
● Use sufficiently dimensioned equipotential bonding conductors if potential differences exist
or are expected between your system components. Equipotential bonding is absolutely
mandatory for applications in hazardous areas.
Technology module TM SIWAREX WP351 HF
Operating Instructions, 01/2020, A5E47521010-AA
Installing
3.3 EMC-compliant installation
21