Material Selection for Cable Tray Systems in Corrosive or Outdoor Environments

When designing cable tray systems for corrosive or outdoor environments, material selection is a critical decision. Hot-dip galvanized (HDG) cable trays have been successfully used for many years. However, aluminum is increasingly becoming the preferred material for cable tray systems. In today’s era of shrinking construction budgets, why do engineers, contractors, and end-users choose aluminum cable trays—even though their initial cost is typically higher than that of hot-dip galvanized steel cable trays? The answer lies in aluminum’s advantages in design, installation, delivery, performance, and total cost of ownership (TCO) over the installation lifecycle.

Design & Installation

Most people are aware that aluminum offers an excellent strength-to-weight ratio. For example, a 36-inch wide, 24-foot long NEMA 20C hot-dip galvanized steel Ladder Cable Tray with 6-inch side rails weighs approximately 200 pounds, while an aluminum cable tray of the same specifications weighs only about 100 pounds. When installers must lift and position cable tray sections 30 feet or higher above the ground, aluminum’s lighter weight means only two installers are needed instead of four.

Aluminum cable trays are also easier to cut on-site—not only because aluminum is simple to cut, punch, and drill, but also because there is no need to apply a protective coating to the exposed edges. The hot-dip galvanized coating on steel must be repaired with zinc-rich paint (also known as cold galvanizing), which is inferior to the original galvanizing, leaving gaps in the steel’s armor against corrosion. Of course, some contractors may not repair the cuts at all, further compromising the cable tray’s corrosion resistance.

Since aluminum cable tray components are extruded, material utilization is more efficient and tolerances are tighter. Some manufacturers leverage this to benefit contractors by creating splice joints and other features that enhance performance and reduce installation work. Additionally, when using cable trays as Equipment Grounding Conductors (EGCs), aluminum’s excellent current-carrying capacity eliminates the need to purchase and install separate EGCs (in qualified industrial installations) and improves installation safety by providing a better fault current path.