Unique Considerations in Cable Routing
Routing Cable Over Metal
If cable is routed over metal, two dangerous situations can occur. First, when routing cable over metal, it’s possible to create a magnetic field which can cause heat that can break down cable insulation. You can minimize this risk by routing cable using the triangular triplex method for arranging cables. For safety, it’s important to avoid having all A-phase, B-phase, or C-phase cables together when routing cable over metal.
Second, routing cable over metal that is exposed to high temperatures can potentially melt the cable insulation. This can create an electrical arc or arc flash that can jump to other objects and cause electrical fires and injury.
Sunbelt Rentals recommends using insulation mats or even 2x4s or 2x6s to create space between the cable and metal. If there is a failure or potential for a short, the wood will act as an insulator, protecting the conductors from shorting against any metal surface.
Routing Cable Over a Sharp Edge
When routing cable, it is imperative to protect the cable from damage. Bending cable over sharp edges of any kind can cause it to snag or tear and damage the wires, which can create a short circuit. Sunbelt Rentals recommends never laying cable over a metal trailer edge or other sharp surface where it could easily be cut.
Routing Cable in High-Traffic Areas
Sometimes cables must be routed in high-traffic areas. Foot and vehicular traffic can cause damage to the cable, resulting in a lower carrying capacity. In addition, cables running on the ground can be a safety hazard. Sunbelt Rentals recommends protecting cable in these situations with cable trays. Cable trays come in a range of sizes and accommodate a range of cable loading requirements. Their heavy-duty construction can withstand traffic and keep cables, people, and vehicles safe.
Routing Cable Vertically
Cable is heavy. Fifty feet of cable weighs approximately 50 pounds. When running cable vertically, that weight can place excessive strain on terminations, panels, or other connected devices. That weight can also stretch the cable insulation or the conductor, which can compromise the cable or loosen the connection. Sunbelt Rentals recommends using a stress relief every 12 feet on vertical applications to keep the cable from being damaged or compromised.
Download our complimentary guide to cable design and layout.
Routing Cable in Wet Environments
Cable routed in low-lying areas can be exposed to water. While the cable and insulation are waterproof and designed to protect the wires from being exposed to water, tears or cuts in the protective insulation can happen. Wires in the cable exposed to water can cause a short circuit, fire, or electrocution. Sunbelt Rentals recommends using pallets or scaffolding as an extra measure of safety to keep cable elevated and out of water.
Routing Cable Overhead
There are a number of reasons why cable should be routed overhead. Vehicular or foot traffic may be too heavy to safely route cable on the ground. Or, small spaces like switchgear rooms, modular server rooms, or substation control rooms preclude running cable on the ground due to sharp turns and corners. In these cases, Sunbelt Rentals recommends safely routing cable overhead using scaffolding or overhead trays.
Routing Cable Through Conduit
Rigid or flexible conduit protects cable from impact and moisture. But when routing cable in conduit, it is important to remember that heat can build up and cause cable to overheat. For example, in a three-phase application, 4/0 type W-2 kV cable is rated at 405 amperes in free air but only 260 amps inside conduit. To solve the problem, you can run two cables, which will split the amperage in half, so neither cable will be pushed to its limits and overheat.
Sunbelt Rentals recommends being aware of the derating factor for every type of cable to use in every type of application.
Sunbelt Rentals is Here to Help
Safety is Sunbelt Rentals core value. That’s why we provide durable cable designed never to fail and optimized for full carrying capacity. During manufacturing, our cable goes through rigorous testing to make sure the insulation integrity meets the highest quality standards. Double insulation ensures our cables also meet the highest safety standards.
To ensure any potential damage is detected immediately, our cable has dual-color insulation. If the outer jacket starts to wear, the inner jacket shows before the damage reaches the wires. Our cable also features additional braiding between the inner and outer layers to make the cable more resilient.
Are you using your own cables? Bring them to us to test and inspect. We’ll perform quality control, check every inch for cuts and scrapes, conduct low-voltage testing, clean the cable, and re-roll it for you.
If you have any questions about the best procedures for cable routing and connections in an application, please give us a call at 866-249-9747 or have us reach out to you.