Strut Channels Guide: Loading Capacity, Usage & Connection Tips

strut channels, often referred to as Kindorf or Unistrut, are standardized structural systems used in the construction and electrical industries for supporting wiring, plumbing, and mechanical components. They consist of a cold-formed metal U-shape with inward-curving lips that provide a continuous mounting point for specialized nuts, bolts, and brackets, allowing for a completely modular support network without the need for welding.

What are Strut Channels and Their Material Grades

A standard strut channel is typically manufactured from 12-gauge or 14-gauge steel. The "U" shape profile features a series of holes (slotted) or a solid back, depending on the mounting requirements. To ensure longevity in various environments, these channels are available in several finishes:

• Pre-Galvanized: Ideal for indoor commercial environments with minimal moisture exposure.
• Hot-Dip Galvanized: Features a thick zinc coating (ASTM A123) for outdoor or industrial use where corrosion resistance is critical.
• Stainless Steel (Type 304/316): Used in food processing or marine environments to resist chemical and salt-air oxidation.
• Aluminum: Selected for applications where weight reduction is a priority without sacrificing structural rigidity.

Structural Strength and Loading Capacity

Understanding how strong a strut channel is requires looking at its beam loading and column loading data. The strength is determined by the "depth" of the channel; the most common size is 1-5/8" x 1-5/8", though "shallow" channels (1-5/8" x 13/16") are used for lighter loads.

Note: These values are based on a safety factor of 1.67 and assume a simple span beam configuration. Always consult manufacturer-specific load tables for safety-critical installations.

Common Applications for Strut Systems

The versatility of the strut channels system makes it the "Lego" of industrial construction. Because the channel serves as a continuous mounting track, it is used for:

• Electrical Conduit Support: Creating trapeze hangers to carry multiple runs of EMT or Rigid conduit.
• Solar Panel Racking: Providing a durable, adjustable base for mounting photovoltaic panels on flat roofs.
• HVAC Ducting: Suspending heavy air handling units and ventilation ducts from concrete ceilings using threaded rods and channel nuts.
• Medical Equipment Grids: Supporting heavy overhead surgical lights or X-ray monitors in hospital settings.

How to Connect Two Strut Channels

Connecting strut channels efficiently is what gives the system its modularity. Connection methods vary based on whether the joint is a linear extension or a 90-degree intersection.

The core of every connection is the channel nut (strut nut). These nuts feature grooves that "bite" into the inward-curving lips of the channel when tightened. For ease of installation, many technicians prefer "spring nuts," which hold themselves in place within the channel, allowing for one-handed bolting of brackets or accessories.

Best Practices for Installation

When cutting strut channels to length, it is vital to deburr the edges to prevent damage to electrical cables and to apply cold-galvanizing spray to the cut ends to prevent rust. When tightening bolts, aim for a torque value of approximately 50 ft-lbs for a 1/2" bolt to ensure the channel nut fully engages with the steel lips without deforming the channel walls.