National Standard Thickness Table for Fireproof Cable Trays

Fire-resistant cable trays are manufactured according to national standards such as UL 568, NEMA VE 1, and NEC, with thicknesses specified based on material type, tray design, and load/span requirements. Overview of StandardsFire-resistant cable trays must comply with multiple standards to ensure safety and performance: UL 568: Covers performance requirements for fiberglass (nonmetallic) cable trays, including fire resistance, mechanical strength, and environmental durability.

NEMA V

E 1: Specifies manufacturing requirements for metal cable trays (ladder, ventilated trough, solid bottom, and channel types), including thickness, load/span classes, and fittings.

NE

C (NFPA 70): Provides installation requirements, ampacity ratings, and fire-resistance considerations for cable trays in electrical systems.

IE

C 61537: International standard for all-metal and nonmetallic cable trays, including mechanical and fire-resistance testing.

Typical Material Thicknesses

The thickness of fire-resistant cable trays varies depending on the material and design: Steel Cable Trays: Pre-galvanized or hot-dip galvanized steel: typically 1. 2 mm to 2. 5 mm for ladder and ventilated trays, depending on span and load class.

Stainless steel (AISI 316L): 1. 5 mm to 3 mm, providing higher corrosion and fire resistance. Aluminum Cable Trays: Alloy trays: 1.

5 mm to 3 mm, selected for mechanical strength and corrosion resistance.

Fiberglass/

Nonmetallic Cable Trays: UL 568-rated trays: thickness ranges from 6 mm to 12 mm, depending on ladder or solid-bottom design and fire-resistance rating (e.g., E30, E60 for 30 or 60 minutes of fire resistance),.

Fire-

Resistance RatingsFire-resistant cable trays are often rated according to the duration they can withstand fire: E30: 30 minutes of fire resistanceE60: 60 minutes of fire resistanceThickness and material selection are adjusted to meet these ratings, with fiberglass trays generally requiring greater thickness than metallic trays for equivalent fire performance.

Load and Span Considerations

Tray thickness is also influenced by: Load class: Light, medium, or heavy-duty cable loadsSpan length: Distance between supportsTray type: Ladder, ventilated trough, solid bottom, or channel Standards like NEMA VE 1 provide tables correlating tray thickness, span, and load class to ensure structural integrity under fire conditions.

Summary

To select the correct fire-resistant cable tray thickness: Identify the material (steel, aluminum, fiberglass). Determine the fire-resistance rating required (E30, E60, etc.).

Consult NEMA V

E 1 or UL 568 tables for thickness based on tray type, span, and load class. Ensure compliance with NEC (NFPA 70) installation requirements. By following these standards, engineers and contractors can ensure that cable trays provide both mechanical support and fire protection in electrical installations.