Location: Central Europe, voltage between phases: 400V. Voltage between phases and ground / neutral: 230V. Frequency = 50 Hz.
When looking at an old 3 phase 1 ground socket with wiring diameter of 3mm2 I discovered that the safety fuse (old, separate fuse for each phase) used to secure this socket is rated at 40A. The cable is installed in a pipe going through insulated walls. Assuming the 3 phases are used to power a machine the maximum capacity per phase according to Wiring capacity is 20A.
Is this the wrong type of fuse?
Or is the capacity of the wires higher under symmetric load where only minimal current is dissipated through the neutral?