Okay, let's break down the requirements for running 480VAC and 24VDC cables in the same cable tray, separated by a solid metallic divider. This situation is covered by the National Electrical Code (NEC) and potentially other local codes or standards.

NEC Considerations



NEC 392.20 (A) (2)

This section of the NEC specifically addresses voltage separation in cable trays. Although it is not always required to run low voltage and high voltage in separate cable trays if there is adequate separation.

Solid Metallic Divider

The use of a solid metallic divider is a key factor in your plan. According to

NEC 392.20(A)(2)(a) 3

A metal barrier can be used for separation.

Regarding Minimum Distance

With a properly installed and maintained solid metal divider, there is no explicitly stated minimum distance requirement in the NEC between the 480VAC and 24VDC cables, or between the cables and the divider. The divider itself provides the necessary physical separation.
The divider has to be secured and connected to the cable tray grounding system to ensure proper grounding.Important Considerations and Best Practices


Divider Construction and Installation

The divider must be constructed of a solid metal that is suitable for the environment (e.g., corrosion-resistant). The divider must be securely fastened to the cable tray to provide a reliable physical barrier. It shouldn't be easily dislodged. The divider must run the full length of the cable tray section where the voltage separation is required. Ensure there are no gaps or openings in the divider that could allow conductors or insulation to contact across the voltage boundary. A ground bonding jumper between the divider and the cable tray should be included as well.2.

Cable Insulation Rating

Verify that the insulation rating of all cables (both 480VAC and 24VDC) is suitable for the highest voltage present (i.e., 480V). This provides an extra layer of safety in case of unforeseen contact or insulation failure.3.

Grounding

Ensure the cable tray system and the metallic divider are properly grounded according to NEC Article 250. Proper grounding is crucial for safety and fault current paths.
4.

Cable Bundling and Support

Even with the divider, avoid excessive bundling of cables. This can trap heat and potentially degrade insulation over time. Properly support the cables within the tray to prevent strain on the conductors and terminations.5.

Accessibility and Maintenance

Consider the accessibility of the cables for future maintenance or troubleshooting. Ensure enough space is available on each side of the divider to work on the cables. Regularly inspect the cable tray system and the divider to ensure it remains in good condition and properly secured.

Example Scenarios Where Additional Spacing Might Be Desirable (Even if Not Strictly Required)



Harsh Environments

In environments with high temperatures, corrosive atmospheres, or excessive vibration, maintaining some extra spacing can further improve cable life and reliability.

High Cable Density

If the cable tray is very densely packed, even with the divider, the extra heat from multiple conductors could be a concern.

Documentation

Document your installation practices, including the use of the divider, the type of cables used, and the grounding methods employed. This will be helpful for future maintenance and inspections.

Disclaimer: I am an AI Chatbot. Consult with a qualified electrical engineer or inspector. They can evaluate your specific installation conditions, local codes, and any specific requirements of your facility to ensure a safe and compliant installation. The NEC is a complex document, and interpretations can vary.By following these guidelines and consulting with qualified professionals, you can safely and effectively run both 480VAC and 24VDC cables in the same cable tray using a solid metallic divider. Flag for review