Safety and Reliability 2.5.5. Protection against external electrical influences Connect the control system to the protective earth conductor to eliminate electromagnetic interference. Ensure practical wiring and laying of cables. 2.5.6. Cable routing and wiring Separate laying of power supply circuits, never together with control current loops: - DC voltage 60 V ... 400 V - AC voltage 25 V ... 400 V Joint laying of control current loops is permissible: - data signals, shielded - analog signals, shielded - digital I/O lines, unshielded - DC voltages - AC voltages 2 - 7