Cables should be run through cable trays first then conduits

Cables are typically installed in cable trays first for support and organization, and conduit is used afterward only when additional mechanical or environmental protection is required.Cable Tray Installation

Cable trays are support structures designed to hold multiple cables in industrial, commercial, or large-scale installations, allowing easy access for maintenance and future expansion . Tray cables (TC or TC-ER) are specifically rated for use in trays and can often run openly without conduit, provided they are secured and protected from mechanical damage . Ladder trays are preferred for power cables because they allow air circulation, reducing heat buildup, while solid-bottom trays are used where electromagnetic interference or aesthetics are a concern .

When Conduit is Required

Conduit is a rigid or flexible tube that provides additional protection against mechanical damage, moisture, chemicals, UV exposure, and rodents . While tray cables can run openly in trays, conduit becomes necessary in certain situations:

• High-risk environments: Areas with forklifts, heavy equipment, or high traffic.
• Outdoor or underground installations: Standard tray cables must be in conduit unless rated for direct burial.
• Hazardous or classified locations: Chemical plants, explosive atmospheres, or damp environments.
• Code or local requirements: Authority Having Jurisdiction (AHJ) or insurance mandates may require conduit even if not specified by NEC . Running cables in conduit after tray installation is not a standard sequence; rather, conduit is used only where additional protection is needed. In most industrial settings, cables are laid in trays first, and conduit is applied selectively for exposed runs or high-risk sections .

Best Practices

• Plan the layout: Use straight, logical paths for trays and minimize sharp bends in conduits .
• Respect bending radius: Conduit bends must not exceed the minimum cable bending radius to prevent damage .
• Leave spare capacity: Avoid overfilling trays to ensure proper heat dissipation and allow future cable additions .
• Grounding: Metallic trays and conduits must be properly earthed, and bonding jumpers should be added at joints if necessary . In summary, cables should be installed in trays first for support and organization, and conduits are added only where extra protection is required, following NEC and IEC standards for safety, mechanical protection, and code compliance .