Internal conduits of cable trays

Internal conduits in cable trays should be arranged in a structured sequence to ensure proper segregation, mechanical protection, and compliance with standards.

Conduit Arrangement Principles

When installing conduits inside cable trays, the sequence and organization are critical for safety, maintenance, and electromagnetic compatibility (EMC). Key principles include: Segregation by Function: Power, control, and communication cables should be separated to prevent interference. Typically, power conduits are placed on one side of the tray, while data or signal conduits occupy another section.

Conduit Type and Material: Use appropriate conduits based on environmental conditions.

PV

C or non-metallic conduits are suitable for indoor, low-stress areas, while metal or flexible metallic conduits are preferred for outdoor or high-stress environments. Routing and Sequence: Conduits should follow a logical path along the tray, avoiding sharp bends and minimizing stress on cables. The sequence often places larger or heavier conduits at the bottom and lighter or smaller conduits on top to maintain stability and load balance.

Spacing and Support: Maintain proper spacing between conduits to allow heat dissipation and ease of maintenance. Supports should follow manufacturer recommendations and IEC 61537 guidelines for mechanical load and bend radius. Earthing and Bonding: Metallic conduits must be grounded at both ends, and bonding jumpers may be added at tray joints to ensure continuity and reduce electromagnetic interference.

Practical Sequence Example

Power Conduits: Place high-voltage or main power conduits at the bottom of the tray for stability and to reduce interference with sensitive circuits. Control Conduits: Position control or instrumentation conduits above power conduits, maintaining separation to prevent signal disruption.

Communication/

Data Conduits: Place telecommunication or data conduits on top or in a separate compartment to minimize electromagnetic interference. Flexible or Special Conduits: Install flexible or liquid-tight conduits in areas requiring bends or moisture protection, ensuring they do not obstruct other conduits. Compliance and StandardsIEC 61537: Provides guidance on tray design, bend radii, and support spacing.

IE

C 60364: Covers cable segregation, voltage drop, and mechanical protection.

EM

C Considerations: Ensure all conduits and trays are bonded and routed to minimize electromagnetic interference, especially in industrial installations.

Summary

The sequence of internal conduits in cable trays should prioritize function-based segregation, mechanical stability, and compliance with IEC standards. Proper arrangement enhances safety, reduces interference, and facilitates maintenance, while ensuring the tray can support the load of all conduits and cables effectively.