The enterprise network is undergoing a major shift in emphasis that impacts cabling." according to Jim Hayes of the Fiber Optic Association, the international non-profit professional society for the fiber-optic industry that develops educational programs and certifies fiber-optic technicians.

"Users expect mobility, demonstrated by the sales of laptops exceeding desktop computers and the popularity of mobile platforms like the BlackBerry and iPhone. Wireless has had growing pains, but with the advent of 802.11n, better cell phone data systems and the likelihood of success for WiMAX, users now have adequate wireless bandwidth practically everywhere and are not crazy about being tethered to a patch cord.

"The network of the future is certainly not recabling every couple of years with another UTP upgrade," he adds. "If 10-Gigabit Ethernet needs to be delivered to the desk, it's probably going to be on fiber, not just for the bandwidth, but also for the lower power consumption. But I'm betting on more mobile applications, with a backbone of fiber connecting wireless access points. That's how cell phone networks are built, as well as many metro Wi-Fi networks. With most large enterprises already depending on fiber backbones, adding adequate wireless access is easy, and, of course, upgrades are simply a matter of replacing wireless access-point hardware."

Zone cabling with fiber to the zone hub is the first step to fiber to the desktop (FTTD). Fiber has been a crucial part of the campus and riser solution for years; now, fiber is reaching the horizontal plane in the structure with a host of economic and functional benefits.

Currently, plenum-approved communications cable dominates new building installs in the United States. Return-air plenum design is still less expensive than ducting feed-and-return HVAC. That brings up another area of concern: supply.

Copper continues to be a cost concern, as well as a supply issue. The most significant supply weak point, however, is the fluoropolymer materials used to insulate high-performance copper-based twisted-pair cabling for plenum-approved cable.

There are only two major producers of the fluorinated ethylene propylene (FEP; commonly known by their trade names: Teflon from DuPont and Neoflon by Daikin USA). If either or both of these material suppliers have a problem, the entire communications industry may have a problem. The National Electrical Code (NEC) may be changed to allow other cable constructions to be approved, but that process with the National Fire Protection Association (NFPA) takes three years.

The NFPA might open the plenum-approved cable exemption to include low-smoke zero-halogen RoHS-compliant cable that is already approved by the European Union. That would still take three years to approve, however.

A shortage of FEP has occurred several times in the history of plenum-approved (CMP-rated) copper cable. During each shortage, the prices rose dramatically, and hybrid constructions were introduced using a mix of other insulating materials to make up for some of the material shortfall. Today, that may not be possible because the higher-performance copper cables (Category 5e, Category 6 and soon Category 6a) cannot function properly with the resultant delay skew caused by different insulation material properties.

"Fire-safe" fluoropolymer materials used in plenum-approved CMP-rated cables generate toxic gases when the cables are exposed to various levels of heat. Since the original approval of the use of CMP-rated cables in the return-air building plenum spaces, there has been no official testing of the cables for any incapacitation factor or toxicity of the gases generated in fires.

According to Chris Pezoulas, vice president of business development at Canadian wiring manufacturer Electec, "Engineers, consultants, specifiers, building owners and contractors alike should look at the cable they are contemplating installing in their air-handling spaces and consider setting a higher standard, not only for themselves, but for anybody that may ever occupy the space they are using.

"With all that we know today about the toxic nature of Teflon, FEP and PFOA, it astounds me that the policy and code makers in North America have ignored the toxicity of plenum cable flame retardants," he adds. "Exposed plenum cable in air-handling spaces is a chemical nightmare."

Frank Bisbee is the president of Communication Planning Corp., Jacksonville, Fla., and editor of "Heard on the Streets," a widely circulated newsletter for the communications cabling industry. The newsletter can be found at www.comnews.com.