What HVAC contractors should know before choosing a cable suspension system
Not All Cable Suspension Is Created Equal
Cable suspension has become increasingly common on HVAC jobsites, particularly for ductwork. But as the technology expands into VAV boxes, VRF systems, air handlers, furnaces, cable tray and conduit racks, an important distinction is becoming clear:
Not all cable suspension systems are designed the same way.
Two products may look similar from the outside, but differences in the cable, gripper, internal locking mechanism, materials and attachment method can significantly affect how a system performs.
For contractors, choosing a cable suspension system should involve more than comparing appearance or price.
Start With Three Questions
According to Larry Dalton, HVAC Sales Manager for Griplock Systems, selecting a suspension system starts with three basic questions:
How are you attaching at the top?
The attachment point and connection to the structure help determine which suspension hardware is appropriate.
How long is the drop?
A short drop close to the deck presents different considerations than a longer suspension.
What are you suspending?
The load and type of ductwork or equipment being supported determine the appropriate cable size, and gripper attachment.
Those three questions provide a simple way to avoid one of the most common mistakes in cable suspension: selecting the product before understanding the application.
Working Load Matters
Cable suspension is not a one-size-fits-all solution.
Different cable sizes and suspension components have different working load limits. Using a lighter cable simply because it costs less can be a problem if it isn’t appropriate for the application.
The system should be selected according to the manufacturer’s specifications for cable size, attachment, load and application.
For typical ductwork, cable can be an effective suspension method. But extremely heavy applications may exceed the working load of a particular cable system. Heavy grease duct, for example, may require a different approach.
The objective isn’t to make cable work everywhere. It’s to use the right suspension system for the application.
Look Beyond the Cable
The cable itself is only one part of the suspension system. The gripper is equally important.
Different systems use different locking mechanisms and internal designs. Earlier cable systems could require a tool to release and adjust the lock, while newer push-button designs make adjustment faster and simpler.
Griplock Systems’ cable grippers feature an all-metal construction with no plastic components and use an internal three-ball-bearing mechanism designed to grip the cable without digging into it. This allows for smooth adjustment while helping maintain cable integrity.
The design of the gripper matters because installers may need to fine-tune the height of ductwork or equipment during installation. A system that can be adjusted quickly and easily can simplify those corrections.
Similar Doesn’t Mean the Same
Cable suspension systems can look deceptively simple, but contractors should look at how the complete system is engineered.
Consider:
- Working load and cable size
- Locking mechanism
- Gripper construction and materials
- Attachment method
- Drop length
- What is being suspended
- Project-specific engineering, code or seismic requirements
Products that look nearly identical can perform differently. The differences may be inside the gripper, in the materials used, or in how the system connects to the cable.
Cable and Threaded Rod Can Work Together
Cable suspension doesn’t make threaded rod obsolete.
Very short drops close to the deck may favor threaded rod. Extremely heavy loads may exceed the working load of a particular cable system. Projects with specific seismic restraint requirements may also require rigid components where the restraint is provided.
That doesn’t mean an entire project has to use threaded rod. Cable and threaded rod can be used together when the application calls for it.
The goal is not to replace one technology with another everywhere. The goal is to select the suspension method that best fits each application.
The Bigger Opportunity
As cable suspension moves beyond traditional ductwork, proper product selection becomes increasingly important.
The technology is now being used for applications ranging from ductwork and VAV boxes to VRF systems, furnaces, air handlers, cable tray and conduit racks.
That expansion makes one thing clear: cable suspension should be treated as an engineered system, not simply a piece of cable and a clamp.
Start with the attachment, drop and load. Then select the appropriate cable and gripper hardware for the application.
The best cable suspension system isn’t necessarily the one that looks the same or costs the least. It’s the one designed and specified to perform the job it’s being asked to do.