Do cable trays need internal connecting plates

Cable trays do not always require internal connecting plates, but splice plates or similar mechanical connectors are commonly used to secure tray sections and ensure structural integrity.

Purpose of Internal Connecting Plates

Internal connecting plates, often called splice plates, are flat metal plates with pre-drilled holes used to join two cable tray sections in a straight line or at angles. They provide mechanical strength, maintain alignment, and allow for secure bolted connections between tray sections, which is especially important for long runs or heavy cable loads . These plates also allow for disassembly or modification of the tray system if needed.

Installation Considerations

• Mechanical Security: Splice plates are bolted to the ends of tray sections to create a strong, reliable connection. They are standard for most tray types and are widely available .
• Alternative Systems: Some manufacturers offer quick-connect systems that snap, slide, or twist together, reducing the need for traditional splice plates. These are faster to install but may be brand-specific and cost more upfront .
• Angles and Junctions: L, T, or cross-shaped plates are used at corners or splits to maintain proper cable routing and structural stability .

Regulatory and Safety Requirements

According to NEC Article 392, cable trays must be installed to support the weight of the cables and maintain proper spacing, but internal connecting plates are not explicitly required by code. They are a mechanical solution to ensure tray alignment and load support. For metallic trays, proper grounding is also necessary, and connections must maintain electrical continuity .

• Voltage Separation: Internal dividers or barriers are only required if separating high-voltage cables from low-voltage or signal cables to prevent interference, not for general tray connection .
• Fill Limits: Ensuring the tray is not overfilled is more critical than the presence of internal plates for safety and compliance .

Conclusion

While internal connecting plates are not strictly mandatory, they are highly recommended for most installations to provide mechanical strength, maintain alignment, and facilitate safe, reliable cable management. Alternative connection methods may be used depending on manufacturer systems, project requirements, and installation speed considerations .