A Contractors Dream

Nonmetallic-sheathed (NM) cable with less pulling resistance? Self-healing aluminum cables? Cable that burns with limited smoke? Cable is not just cable anymore. If you are like me, you grumble when things go awry. For example, the installation problems that occur with NM cables: jackets that tear like tissue paper, high pull resistance, jackets without indication of specific gauge wire and illegible data on sheath. Not to mention buried aluminum cables. You nick that cable during installation, and it is only a matter of time before its demise.

At times it seemed like all other products-except cabling-were making technological leaps and bounds. Boy, was I wrong. At least two companies I found were quietly doing R & D and have come out with some real usable advances in cable products for us in the field.

Research and development

Most electricians probably do not consider the time that goes into new cable, but a look at Southwire's D.B. Cofer Technology Center in Carrolton, Ga., might change their minds. At the 50,000-square-foot center, new products are stretched, stressed, heated, vibrated, scanned by electron microscopes, run through optical spectrometers and subjected to impulse-generator testing that can simulate lightning surges on medium- and high-voltage cable. There is a metallurgy department, an area devoted to experimental insulations and their compounds, and electrical and mechanical testing areas.

“The Cofer Technology Center's capabilities are many. It can simulate production lines. It can test new ideas for production as well as create future products in new ways. It can test for product quality,” wrote Cofer director Vince Kruse. “The center is a UL-certified testing facility and also has the requisite high-voltage laboratory capability for testing the company's electric utility products to industry standards. In this way, the center has the ability to continually qualify the products the corporation produces.”

An easy pulling cable

Insulation and jacketing development is a big part of Cofer's mission. The center's compound/extrusion area has an experimental extrusion line, which insulates wire and cable under development, and a vertical tray flame test chamber that subjects cable-tray products to a 70,000- or 210,000-BTU level test, and a blown film tower that can stretch polymer to 0.001 inch thick for quality assurance.

Not sophisticated enough? How about a gas chromatograph to troubleshoot PVC compounds, a Fourier transform infrared microscope for contaminant detection in jacketing material and a torque rheometer for blending insulation compounds. What are some of the results of their insulation research? Southwire has developed an NMB cable called SIMpull with an infused-membrane jacket system claimed to reduce pulling friction through wooden joists, rafters, etc., by 50 percent and eliminate the need for oversized drilled holes or cable lube in tight pulls.

Color-coding and self-healing

Sometimes development means responding to users. In 2002, Southwire introduced color-coded cable, which helps ease installations and inspections, and I like to think my book, “Wiring a House” was a catalyst. In it, I prodded all cable manufacturers to develop coded cables. Maybe someone was listening.

Sometimes research means providing new solutions to old problems. I have seen entire conductors “eaten” or corroded through-some took months, others took years. I had one cable to an outbuilding eat through in less than six months, and it was in conduit. It has been reported that some large utilities are documenting 3,000 to 6,000 600V underground failures per year. Each failure costs from $500 to $1,000 to repair. Don't forget the loss of good public relations when a customer's front yard is dug up with a backhoe.

Normally, it starts with minor insulation damage during the installation-or just a sharp rock cutting into the cable from freezing and thawing. Once moisture enters the cable, the electrolytic corrosion begins. To stop this cycle, Southwire developed a patented cable design, where “grease” flows into insulation breaks and blocks the moisture entrance.

Testers at Cofer subjected cables to high-voltage DC impulses. At 130kV, the insulation blew out. Within 30 minutes, the SureSeal compound had sealed the hole. With the test run again, the same section of cable withstood impulses of well over 70kV.

Futuristic applications in use

Southwire also designed, built, installed and tested a “real-world” high-temperature superconducting (HTS) system that powers three of its Carrolton manufacturing plants. Its cables are rated at 12.4kV, 1,250A, 60hz and cooled with pressurized liquid nitrogen. The project, a joint effort with Oak Ridge National Laboratory with sponsorship by the Department of Energy, began in 1997, was put on line in January 2000, and involved the first superconducting cable system to supply power to a live load.

The company is scheduled to test its long-length superconductor site in Columbus, Ohio, this year. David Lindsay, director for Ultera, a joint venture between Southwire and NKT cables of Denmark, said the Columbus project is ready to energize next spring. The Ultera Web site outlines superconducting cable's ability to move bulk power at lower voltages, giving it possible applications at or near generating facilities.

According to the Web site: “In traditional generating facilities, step-up transformers may be moved to locations farther away from the generator by moving the bulk power at the generating voltage. Newer forms of generation such as fuel cells and wind power promise to change the landscape of power generation around the world.

“HTS cables offer a solution to connect these low- to mid-power level generating facilities to the net at lower voltages. This low-voltage connection simplifies integration of these forms of generation. Cold dielectric HTS cables offer the benefit of very low impedance when compared to conventional cables.”

Limited smoke classification

But Southwire is not alone. AlphaGary and DuPont have joined R & D forces to improve the fire and smoke safety performance of data cable within air plenums. With the need for fast communications within a company from one department to another, more data cables were being placed in air plenums and industry leaders wanted to create a limited-smoke class sheath.

If there were a fire or just an overheating conductor problem, the smoke and chemicals from the fire would follow the duct work throughout the building, emptying into the communication rooms, contaminating the highly sensitive electronic data panels. Jacketed cable with limited smoke capability could reduce that problem. So, a limited smoke classification was created and many manufactures make such a cable.

But DuPont and AlphaGary wanted something even better-they wanted to prevent the byproducts of the smoke and fire from creating a carbon-type coating on electronic printed circuit boards. And they did. The cables' primary wires are insulated with DuPont Teflon FEP. The jacket is made with Smokeguard FP with Teflon, from AlphaGary.

To qualify as DuPont certified, cable must be tested and verified by independent testing labs, such as Underwriters Laboratories Inc., and meet the following requirements:

°Telecommunications Industry Association (TIA) Category 5e, Category 6 or higher standards for electrical performance

°Primary wire insulation constructed of DuPont Teflon FEP

°Jacket construction of Smokeguard FP with Teflon

°Meet or exceed the most stringent NFPA or UL Limited combustible requirements for cable flame spread, fire load and smoke generation

°Not contain any substances or components regulated under RoHS and WEEE directives

°Completely recyclable of both copper and plastics at end-of-life

°Made by DuPont-authorized cable manufacturers

Like a carpenter hammering a nail, pulling cable is second nature for electricians. It is easy to think that cable is just cable, but ongoing cable R & D attempts to make our jobs easier and the things we build safer. Who doesn't dream of a better way to do his or her job? R & D techs bring those dreams into reality. EC

CAULDWELL is a contractor, master electrician, master plumber, home inspector, author and speaker who lives in Rocky Mount, Va. He can be reached at ltmtnele@yahoo.com


About the Author

Rex Cauldwell

Freelance Writer
Rex Cauldwell is a contractor, master electrician, master plumber, home inspector, author and speaker who lives in Rocky Mount, Va. He can be reached at ltmtnele@yahoo.com .

Stay Informed Join our Newsletter

Having trouble finding time to sit down with the latest issue of
ELECTRICAL CONTRACTOR? Don't worry, we'll come to you.