Allowable deviation of cable tray wall thickness

The allowable deviation in cable tray wall thickness typically follows NEMA VE 1 and IEC 61537 standards, with tolerances generally around ±10% of the nominal thickness depending on material and tray type.

Standard Wall Thickness and Tolerances

Cable trays are manufactured in various materials such as steel, aluminum, stainless steel, and fiberglass, and the wall thickness is critical for mechanical strength, load capacity, and long-term durability . While exact tolerances can vary by manufacturer and material, the following general guidelines apply:

• Steel and Aluminum Trays: Wall thickness deviations are usually ±10% of the nominal thickness. For example, a 2 mm steel tray side rail may vary between 1.8 mm and 2.2 mm.
• Fiberglass or Nonmetallic Trays: Tolerances are slightly wider due to manufacturing processes, often ±15%, but must still meet UL 568 or IEC 61537 performance requirements .
• Ladder, Channel, and Wire Mesh Trays: Each tray type has specific thickness requirements to support the intended cable load and span. Ladder trays, designed for heavy loads, require stricter adherence to thickness tolerances to prevent deflection .

Compliance with Standards

• NEMA VE 1 specifies manufacturing requirements for metal cable trays, including material thickness and load/span class designations .
• IEC 61537 provides international standards for all-metal and nonmetallic cable trays, including tests for mechanical strength and dimensional tolerances .
• NEC Article 392 and CSA C22.1 Part 1 provide installation and safety requirements but do not explicitly define wall thickness deviations; they rely on compliance with NEMA or IEC standards .

Practical Considerations

• Always verify the manufacturer's specifications for allowable thickness deviations.
• Ensure that the tray thickness is sufficient to support the intended cable load and span between supports without excessive deflection .
• For critical installations, consider inspection or measurement of tray wall thickness to confirm compliance with design tolerances. In summary, while exact numbers may vary, ±10% of nominal thickness for metal trays and ±15% for nonmetallic trays is a widely accepted engineering practice, ensuring structural integrity and compliance with NEMA and IEC standards.