ABB AC31 Assembly And Operation Manual page 12

AC31 Adapters
System data and CS31 bus system data > CS31 bus system data
Incorrect cable laying:
1.3.2.3 Earthing
In order to avoid disturbances, earth the cable shields directly.
Current carrying Choose direct earthing if it can be ensured by means of current carrying metal connections
capacity (steel constructions, earth bars, etc.) that no potential differences can occur.
12 3ADR010122, 8, en_US 2018/09/24