Stacking Up Cable Tray

In the ever-growing world of telecommunications, many factors come to bear when designing a complete and robust cable system—from the type of technology to the level of cable and type of distribution. Often overlooked, however, is the type of cable support or conveyance system, i.e., cable tray and its accessories.

01/01/2004


In the ever-growing world of telecommunications, many factors come to bear when designing a complete and robust cable system—from the type of technology to the level of cable and type of distribution. Often overlooked, however, is the type of cable support or conveyance system, i.e., cable tray and its accessories.

In my experience as a contractor and through conversations with field installers, I've determined that the most common cable tray technologies available are as follows:

Wire basket tray

Pros: From the installer, designer and owner's point of view, this system is becoming the preferred tray for low voltage conveyance. It is easy to install and, as a result, produces lower labor costs compared to other types of tray. Wire basket tray is light and easy to work with in both overhead and underfloor environments and offers several options for attaching to a parallel running wall or for suspension from a permanent structure.

Cons: Oftentimes, the clean cutting tool recommended by the manufacturer still leaves some jagged edges that require additional smoothing with a high-speed grinder or metal file.

Solid-rail ladder rack

Pros: This type of tray is robust in design and excellent for outdoor or harsh environments, such as refineries, manufacturing plants and warehouse areas. It is also effective for high-pair trunk telephone cables. Solid-rail ladder rack has a high NEMA rating and can be installed indoors or outdoors.

Cons: Bends, offsets and radiuses are sometimes difficult to accomplish. Although the tray manufacturer will sell pre-assembled offsets, radiuses and bracketry to accomplish these tasks, field conditions often make it impossible to install, so field fabrication is required.

Because this is a specialty type of tray for either high-voltage cable or high-pair-count trunk-type cables, the price tends to be higher than most other tray systems.

Center spine tray

Pros: Installing center spine trays reduces the number of supports required, as only one is needed for the center spine of the tray. This type of tray is fairly light and is very quick to install if the routes are straight and do not require a lot of up and down offsets or bends.

Cons: Oftentimes with the center spine, one side of the tray gets overloaded with cables causing the tray to list or twist to one side, jeopardizing the integrity of the center support fastening hardware.

U-tray

Pros: U-trays work best when installed along a flat wall, above a ceiling or under a raised floor. Pre-set mounting holes take away guesswork as to where uniform mounting will occur. U-tray is lightweight, inexpensive to install and available in any size.

Cons: If the tray is not through-bolted or securely fastened, the inherent design does not provide for a very secure support. Although it's very easy to bend and offset, the main support bar is often bent before or after initial bends and has a very unaesthetic appearance.



Common cable tray technologies

Wire basket tray

Solid-rail ladder rack

Center spine tray

U-tray



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