Unshielded cable tray wiring

Unshielded tray cables are ideal for low electromagnetic interference (EMI) environments, offering cost-effective, flexible, and easy-to-install wiring solutions for power and control applications.

Overview of Unshielded Tray Cable

Unshielded tray cables consist of two or more insulated conductors, a ground conductor, and a protective jacket, typically made of PVC or XLP for mechanical and environmental protection . They are designed for low electromagnetic frequency (EMF) environments, where signal degradation, crosstalk, or EMI is minimal . These cables are commonly used for power distribution, control circuits, and instrumentation in industrial and commercial settings .

Advantages

• Cost-effective: Less expensive than shielded cables due to the absence of EMI shielding .
• Lightweight and flexible: Easier to bend and route through tight spaces in cable trays .
• Simplified installation: No need for grounding the shield, reducing labor and complexity .

Limitations

• Not suitable for high EMI areas: Exposure to motors, variable frequency drives (VFDs), or other high-interference equipment can cause signal degradation or equipment failure .
• Limited protection: Unshielded cables do not prevent external electromagnetic noise from affecting sensitive circuits .

Installation Considerations

• Cable tray selection: Use ventilated or solid-bottom trays depending on heat dissipation and environmental exposure .
• Spacing and support: Maintain proper spacing and secure cables every 6 feet or as required by NEC Article 392 to prevent sagging and mechanical stress .
• Segregation: Keep unshielded power and instrumentation cables separate to minimize crosstalk; barrier strips or separate trays are recommended .
• Bend radius: Follow the minimum bend radius specified by the manufacturer to avoid conductor damage .

Common Cable Types

• Type TC (Tray Cable): Rated for 600V, suitable for power and control circuits, can be installed indoors, outdoors, or in cable trays .
• Type ITC (Instrumentation Tray Cable): Available in unshielded or shielded versions, used for low-voltage instrumentation and control circuits .
• PLTC/ITC dual-rated cables: Can be installed in industrial environments with continuous support and mechanical protection .

Best Practices

• Use unshielded tray cables in low-EMF environments to maximize cost and flexibility.
• Avoid running unshielded cables near high-voltage or high-frequency equipment.
• Ensure compliance with NEC requirements for cable support, spacing, and installation .
• Consider upgrading to shielded cables if future EMI sources may be introduced. Unshielded cable tray wiring provides a practical and economical solution for many industrial and commercial applications, but careful planning and adherence to installation standards are essential to maintain performance and safety.