Should the control cable be routed through the low-voltage cable tray

Control cables should generally not be routed together with high-voltage power cables in the same tray; they should be segregated in dedicated low-voltage or instrumentation trays to minimize interference and comply with standards.

Key Guidelines for Control Cable Routing

Segregation by Voltage and Function: Control cables, which are typically low-voltage, should be routed separately from high-voltage power cables. This separation reduces the risk of electromagnetic interference (EMI) that can disrupt signal integrity in control systems . Industry best practices recommend placing power cables above and control or instrumentation cables below in multi-level trays . Minimum Spacing Requirements: When separate trays are not feasible, maintain a minimum vertical or horizontal distance between power and control cables. Standards often suggest at least 200–300 mm (8–12 inches) of separation . Divider partitions or compartmentalized trays can be used to maintain isolation if space constraints exist . Shielding and Grounding: For sensitive control signals, shielded cables may be used, but shielding alone does not replace the need for physical separation . Proper grounding of trays and cable shields is essential to reduce EMI and maintain system reliability . Compliance with Standards: Routing should follow NEC articles (e.g., 725.136, 760.53) and IEC standards (e.g., IEC 60364, IEC 61537) for cable segregation, mechanical protection, and earthing . Class 2/3 circuits must not share space with Class 1 circuits unless installed according to Class 1 wiring methods . Practical Routing Considerations: Use the shortest practical path, avoid unnecessary bends, and provide easy access for maintenance. If trays intersect, cross cables at 90-degree angles to minimize coupling . Ensure that trays are not overloaded to prevent mechanical stress and overheating .

Conclusion

Control cables should be routed in dedicated low-voltage or instrumentation trays rather than through trays carrying high-voltage power cables. If space constraints require proximity, use physical dividers, maintain minimum separation distances, and ensure proper shielding and grounding. Following these practices ensures signal integrity, reduces EMI, and maintains compliance with NEC and IEC standards.