Permissible Thickness Standards for Galvanized Cable Trays

Galvanized cable trays typically have steel sheet thicknesses ranging from 1. 5 mm to 3 mm, with zinc coating thickness of at least 45 µm for standard components.

Steel Sheet Thickness

The base and side plates of galvanized cable trays generally range from 1. 5 mm to 3 mm in thickness, depending on the tray type, load requirements, and span length. Heavier components such as brackets and supports, which often exceed 3 mm, require higher mechanical strength and correspondingly thicker coatings to maintain corrosion resistance.

Zinc Coating Thickness

The zinc coating provides corrosion protection and is measured in two ways: Local thickness: The minimum zinc thickness at any single test point, typically measured with a magnetic thickness gauge. For standard tray sheets, this should be no less than 45 µm, corresponding to a coating mass of 325 g/m². Heavier components like supports may require ≥55 µm.

Mean coating mass: The average zinc mass per unit area of the entire tray, determined by gravimetric methods. This ensures overall uniform protection across the tray surface.

Coating Quality and Standards

The galvanized coating should be continuous, uniform, and smooth, with minor variations in color allowed. Defects such as bare spots, blisters, or excessive zinc dross are not permitted. Standards for electro-galvanized trays are defined in GB/T 26941.

1-2011, while hot-dip galvanized trays follow NEN-EN-ISO 1461 for minimum coating thickness and corrosion protection.

Summary

Tray sheet thickness: 1. 5–3 mm (base and side plates)Bracket/support thickness: >3 mmMinimum zinc coating: 45 µm (standard), 55 µm (heavy components)Mean coating mass: ≥325 g/m² for standard traysStandards: GB/T 26941. 1-2011, NEN-EN-ISO 1461 These specifications ensure that galvanized cable trays provide adequate mechanical strength, corrosion resistance, and long-term durability in electrical installations.