Requirements for galvanized steel plates for cable trays

For cable trays, pre-galvanized steel (ASTM A653 SS, G90) is suitable for indoor dry environments, while hot-dip galvanized steel (ASTM A123) is required for outdoor or high-moisture conditions.

Pre-

Galvanized Steel (PG)Pre-galvanized steel is mill-coated with zinc and is ideal for dry indoor environments such as office buildings or clean factories. The coating thickness typically ranges from 12 to 20 microns (Z120–Z275), providing moderate corrosion protection.

P

G steel is economical and polished, but it is not suitable for outdoor or wet locations, as rust may appear within 6–12 months if exposed to moisture. According to Eaton specifications, pre-galvanized steel for cable trays should meet ASTM A653 SS, Grade 33, coating designation G90, with hardware finished in electro-galvanized zinc per ASTM B633.

Hot-

Dip Galvanized Steel (HDG)Hot-dip galvanized steel is immersed in molten zinc, creating a thicker, more durable coating that protects all edges, holes, and corners. The coating thickness usually ranges from 65 to 85 microns, offering long-term corrosion resistance for outdoor, coastal, or high-humidity environments.

HD

G steel is fabricated from structural quality steel meeting ASTM A1011 SS, Grade 33 for 14 gauge and heavier, or ASTM A1008, Grade 33 Type 2 for 16 gauge and lighter, and is galvanized after fabrication in accordance with ASTM A123. This ensures the cable tray can withstand rain, salt air, and other corrosive conditions for 20 years or more.

Selection Guidelines

Indoor, dry areas: Use pre-galvanized steel (PG) for cost efficiency and adequate protection. Outdoor or high-moisture areas: Use hot-dip galvanized steel (HDG) to prevent premature rusting and ensure long-term durability. Mechanical strength: Both PG and HDG steel should meet structural quality requirements and comply with NEMA VE 1 or IEC 61537 for load-bearing capacity.

Hardware: Ensure bolts, nuts, and splice plates are compatible with the chosen galvanized finish to maintain corrosion resistance. Choosing the correct galvanized steel grade ensures safety, longevity, and compliance with electrical and mechanical standards for cable tray installations.