Thickness of Fireproof Cable Trays for Low Voltage Cables

The thickness of fireproof cable trays for low-voltage cables depends on the tray material, cable load, and fireproofing system, typically ranging from 1. 2 mm to 2. 5 mm for steel trays, with additional insulation wraps for fire protection.

Material and Mechanical Considerations

For low-voltage cables, indoor cable trays are usually made of painted steel or galvanized steel, while outdoor or corrosive environments may require stainless steel, aluminum alloy, or fiberglass-reinforced plastic trays. The tray thickness should be sufficient to support the weight of the cables without deformation, which generally falls between 1. 2 mm and 2.

5 mm for steel trays, depending on the span and load. Mechanical strength is critical to prevent sagging or failure under full cable load.

Fireproofing Measures

To achieve fire resistance, cable trays can be equipped with fireproof insulation wraps such as FyreWrap®, which provides a protective enclosure around the tray and maintains circuit integrity during a fire.

Fyre

Wrap consists of a high-temperature Insulfrax® core encapsulated in aluminum foil and fiberglass-reinforced scrim, offering both thermal insulation and mechanical protection. This system is FM Global approved and meets ASTM E-1725 and ASTM E-1529 standards, ensuring performance for trays with zero to full cable loading.

Design and Installation Guidelines

Tray width and thickness should be selected based on the number and weight of cables to ensure mechanical stability. Support spacing should follow standards such as NEMA VE-1 and VE-2, typically using a 1/4 span support method to minimize stress and deflection. Segregation of power and signal cables is recommended to reduce electromagnetic interference, with low-voltage cables often routed in dedicated trays.

Ventilated or solid-bottom trays can be used depending on heat generation and aesthetic requirements, with solid covers providing additional fire protection.

Summary

For low-voltage applications, steel cable trays with a thickness of 1. 2–2. 5 mm are commonly used, with fireproofing achieved via specialized insulation wraps like FyreWrap® for critical installations.

The exact thickness should be determined based on cable weight, tray span, and environmental conditions, while ensuring compliance with mechanical and fire-resistance standards.