New National Standard for Galvanized Cable Trays

The latest national standard for galvanized steel cable trays is T/CECS 31-2017, which specifies galvanizing processes, zinc coating thickness, and structural requirements for industrial and civil installations.

Overview of the Standard

The T/CECS 31-2017 standard is the most recent national guideline for steel cable trays, covering both indoor and outdoor applications, as well as high and low voltage power transmission and distribution projects . It defines the galvanizing processes and the corresponding zinc layer thickness required to ensure durability and corrosion resistance under various service conditions . The standard emphasizes that hot-dip galvanizing provides superior bonding strength, compactness, and long-term maintenance-free performance compared to electroplated coatings .

Material and Structural Requirements

• For ladder-type trays with a width between 150mm and 400mm, the side plate and rung thickness must be at least 1.2mm, and the cover plate at least 0.6mm .
• For trays wider than 500mm and up to 800mm, steel trays require a bridge thickness of 2.0mm, aluminum alloy trays 2.2mm, and fiberglass trays 4.5mm .
• The service life and corrosion resistance of galvanized parts are directly related to the zinc coating thickness, which should be increased for more stringent environmental conditions .

Galvanization Processes

• Hot-dip galvanizing: Steel components are continuously passed through a molten zinc bath, forming a durable, sacrificial protective layer that resists corrosion and mechanical damage .
• Electro-galvanization: Provides a thinner zinc coating suitable for less demanding environments, but with lower durability compared to hot-dip galvanizing .
• The corrosion resistance of galvanized trays is proportional to the zinc layer thickness, which is specified according to the intended service conditions .

Compliance and Related Standards

• NEMA VE 1 specifies manufacturing requirements for metal cable trays, including ladder, channel, wire mesh, and solid bottom types, harmonized with the Canadian Electrical Code .
• ASTM standards such as A123, A653, and B633 define zinc coating specifications for hot-dip and electrodeposited galvanized steel .
• IEC 61537 provides international requirements and testing for cable tray systems, including metal and nonmetallic types .
• Installation guidelines are provided in NEMA VE 2, ensuring proper handling, support, and maintenance of galvanized cable trays .

Practical Implications

The updated standard ensures that galvanized cable trays are structurally robust, corrosion-resistant, and suitable for diverse industrial and civil applications. Engineers and contractors should select the appropriate galvanization process and zinc thickness based on environmental exposure, load requirements, and service life expectations . By adhering to T/CECS 31-2017 and related standards, installations achieve long-term reliability, safety, and compliance with national and international electrical codes.