Beckhoff AX8000 Series Operating Instructions Manual page 80

Electrical installation
80 ───
Example of the design of the current-limiting circuit breakers
in the system group
Rated output current of the axis modules is 18 A for AX8118-0000
and 8 A for AX8108-0000 = 26 A
Total rated output current = 26 A
The system connection must be fused with at least 26 A.
Select the next higher standard level for this according to UL 508A,
Tab. SB4.2. This corresponds to class "J" with 40 A.
AX8000 Version: 1.1