Power and low-voltage circuits should be physically separated in cable trays using dividers, barriers, or compartmentalized enclosures to ensure safety, signal integrity, and NEC compliance.

Key Principles for Separation

1. Safety and Code Compliance High-voltage power cables must be separated from low-voltage or limited-energy circuits to prevent electrical hazards and comply with the NEC 2026. NEC Articles 300.3(C), 725.136, 760.53/760.136, and 805 specify that Class 1 (power) circuits cannot share the same space with Class 2 or 3 circuits unless proper reclassification and installation methods are applied . Physical separation reduces the risk of electrical shock, fire, or accidental contact. 2. Electromagnetic Interference (EMI) Mitigation Power cables generate fluctuating magnetic fields that can induce noise in nearby low-voltage communication or control cables, causing signal degradation, packet loss, or cross-talk . Maintaining minimum separation distances, using metallic barriers, or installing shielded cables can reduce EMI. Standard practice recommends at least 50 mm (2 inches) for short runs, with larger distances (up to 12 inches) for high-current or long parallel runs . 3. Tray Layout and Enclosure Methods

• Layered Separation: Place power trays above low-voltage or instrumentation trays to minimize interference .
• Dividers and Partitions: Use metal or listed barriers within trays to create compartments for different voltage classes, especially in congested areas .
• Compartmentalized Trays: Prefabricated trunking or multi-level trays provide geometric separation and can act as partial EMI shields .
• Perpendicular Crossings: When power and low-voltage cables must intersect, they should cross at 90 degrees to minimize parallel exposure and reduce inductive coupling . 4. Inspection and Maintenance Considerations Proper separation ensures inspection readiness and reduces rework. NEC 2026 clarifies that mixed-voltage routing must follow barrier requirements and maintain consistent spacing in risers, plenums, and shared pathways . Tray layouts should allow easy access for maintenance, troubleshooting, and future upgrades . 5. Best Practices Summary
• Use separate trays or compartments for power and low-voltage circuits.
• Maintain minimum NEC-specified separation distances and consider exceeding them for high-current or sensitive circuits.
• Employ metallic dividers or prefabricated trunking to reduce EMI.
• Arrange trays with power above low-voltage circuits and avoid unnecessary crossovers.
• Ensure all trays are properly grounded to improve EMC performance and safety . By following these guidelines, installations achieve safe, reliable, and code-compliant separation between power and low-voltage circuits while minimizing interference and maintaining signal integrity.