Cables and wires should not share the same cable tray

Power cables and low-voltage or communication cables should not share the same cable tray unless strict separation or shielding measures are implemented.

Regulatory Standards

According to the National Electrical Code (NEC) Article 300. 3(C)(1), mixing power and low-voltage cables (such as control, communication, or instrumentation cables) in the same raceway or tray is generally prohibited unless specific separation or shielding requirements are met. Similarly, IEC 60364-5-52 recommends physical separation or shielding to prevent electromagnetic interference (EMI) between high-power and sensitive low-voltage circuits.

Risks of Mixing Cables

Electromagnetic Interference (EMI): Power cables generate magnetic fields that can disrupt signals in communication or control cables. Voltage Induction: High-voltage cables may induce unwanted voltages in nearby low-voltage circuits, potentially damaging equipment. Fire Hazards: Overheating can occur if cables are improperly grouped, increasing the risk of fire.

Best Practices for Safe Co-LocationIf it is unavoidable to run different types of cables in the same tray, the following measures are recommended: Physical Separation: Use dividers to maintain a minimum gap (commonly 30 cm) between power and low-voltage cables. Shielding: Employ shielded low-voltage cables and ensure proper grounding to reduce EMI. Zoning: Segregate power and control circuits into different sections of the tray.

Tray Fill Compliance: Ensure the tray is not overfilled, as excessive cable density can reduce cooling and increase fire risk.

Practical Considerations

In industrial plants and smart buildings, separate trays are often used for power and instrumentation to maintain signal integrity and comply with safety standards. While some NEC provisions allow multi-conductor cables rated 600V or less to share a tray, this is conditional and requires careful assessment of insulation, spacing, and EMI risks. Nonmetallic trays and solid-bottom trays can provide additional shielding but may affect heat dissipation, so tray type selection is important.

Conclusion

Cables and wires should generally not share the same cable tray unless strict separation, shielding, and compliance with NEC or IEC standards are implemented. Prioritizing separate trays for power and low-voltage circuits is the safest approach to ensure system reliability, prevent interference, and reduce fire hazards.