When routing tray in either the ceiling or underfloor, vertical changes must often be made to address installations of plumbing; heating, ventilation, and air conditioning (HVAC); and other support infrastructure
problem
When routing tray in either the ceiling or underfloor, vertical changes must often be made to address installations of plumbing; heating, ventilation, and air conditioning (HVAC); and other support infrastructure. During cable installation or moves, adds, and changes, the cable being pulled will sometimes attempt to "leave the tray" when encountering these vertical obstacles.
solution
The addition of a simple "retainer" or guide in the form of a roller will ensure the protection of the cables during their installation, and that the cables remain within the tray system. These rollers will make sure that your cables can't snag or be damaged by obstacles within their path. Even in the case of a slight tray bend, you can ensure complete cable protection with this cost-effective solution.
procedure
Determine the width of your tray, and cut a section of electrical metallic tubing (EMT)/conduit or other rigid metal tubing to fit within the interior width dimension of the tray.
Slide a tension spring through the rigid metal tubing. Make sure the pipe section has the ability to freely roll or turn on its support (the tension spring).
Next, attach each end of the tension spring to the top rails of the tray where there is a change in elevation. Most tension springs have dual hooks on each end to attach to the rails. If the spring does not have hooks, you can use either a section of wire or a threaded bolt, nuts and washers to attach the roller to the tray. A tight fit between the pipe and the inside of the tray will avoid any potential of the cables pinching in the corner, but be sure the roller can turn on its support.
Finally, insert a similar retainer/guide at each vertical juncture of the tray, as shown in the illustration.
Use a "retainer" to guide your cables past an HVAC duct.
Click here to enlarge image
In this example, you want to use a minimum of two retainers to initially help guide the cables past an HVAC duct.
Terry McCrary is team manager of new product development at GS Metals Corp.-Flextray Division (Pinckneyville, IL); www.flextray.com.
