Table of Standard Values ​​for Smoothness of Cable Trays

Cable tray smoothness is typically defined by surface finish and permissible irregularities to ensure safe cable installation and minimal abrasion, as guided by IEC 61537 and NEMA VE 1 standards.OverviewCable tray smoothness is critical to prevent damage to cable insulation, reduce friction during cable pulling, and ensure electrical safety. Standards such as IEC 61537 and NEMA VE 1 provide guidelines for metallic cable trays, including steel, stainless steel, and aluminum, but do not always specify a single numeric roughness value. Instead, smoothness is generally ensured through:Surface finishing: Galvanized, powder-coated, or stainless steel surfaces are used to minimize roughness and corrosion .Edge treatment: All cut edges and bends must be deburrred or rounded to prevent cable damage .Weld and joint quality: Welds should be smooth, with no protrusions exceeding 1–2 mm, ensuring cables can slide without snagging .Mesh or perforation design: For wire mesh trays, the wire diameter and spacing are selected to avoid sharp edges and maintain smooth cable support .Typical Smoothness GuidelinesTray TypeSurface FinishEdge TreatmentNotesSteel (galvanized)Hot-dip or pre-galvanized, smooth coatingDeburred edges, rounded cornersSuitable for industrial environmentsStainless SteelPolished or brushed finishSmooth welds, rounded edgesHigh corrosion resistance, minimal frictionAluminumAnodized or powder-coatedSmooth bends, no sharp burrsLightweight, corrosion-resistantWire MeshWelded joints, smooth wire endsRounded or capped wire endsPrevents cable snagging and abrasionPractical ConsiderationsCable pulling tests: IEC 61537 recommends testing trays for mechanical performance, including deflection and load, which indirectly ensures smoothness is adequate for cable installation .Electrical continuity: Smooth surfaces also help maintain low-resistance bonding across joints (