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Structured Health Risks

The industry currently has two burning issues it needs to confront. One relates to environmental air plenums being turned into a toxic fire hazard. The other involves the lead used as a stabilizer in many plenum-rated cables becoming an airborne toxin. There are new developments occurring on both fronts.

May 1, 2003  

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In thousands of office buildings in Canada and the U.S. reside millions of miles of telecommunications cable that is stamped plenum-rated, but that might not necessarily mean that workers sitting at their workstations are safe if a fire takes place.

Such health and safety concerns raise two related, yet highly complex and controversial issues: Whether environmental air plenums, which are crammed with miles of twisted cable — much of it abandoned – have turned into a toxic fire hazard, potentially leading to injury or death from smoke inhalation; and whether the lead used as a stabilizer in many plenum-rated cables can become an airborne toxin, thus triggering a host of medical conditions, such as cardiovascular and kidney problems, impotence and short-term memory loss.

Although emissions during product use are considered negligible, lawsuits in California under Proposition 65 are challenging such views. (see sidebar)

These issues are gaining more prominence, notably because environmental, health and safety concerns are becoming increasingly important, not only in North America, but also in Europe.

For one, lead compounds, which are used in the manufacture of plenum cables, are on the hot list of banned products. For example, the European Union Directives on Waste Electrical and Electronic Equipment (WEEE) can have far-reaching consequences for Canadian manufacturers.

“The proposed WEEE directive requires end-of-life equipment to be collected for recovery, recycling and re-use, placing the main responsibility on the manufacturers of such equipment,” reports the Lowell, Mass.-based Massachusetts Toxics Use Reduction Institute (TURI) in its comprehensive 2002 report, Environmental, Health and Safety Issues in the Coated Wire and Cable Industry.

In most office buildings, cable goes from the building’s centre core, where the cable closet sits, and then runs along the ceiling plenums to individual workstations.

Typically, three cables run to each workstation: One voice and two data. The plenum space, which is either above ceilings or below raised floors, acts a conduit of air through heating, ventilation and air conditioning (HVAC) systems.

During a fire, it can also act as a channel of flame and smoke, allowing it to spread quickly. Thus, it is critical that all materials in the plenum are sufficiently flame-retardant to allow people to safely evacuate a building during a fire. Yet, current codes and standards do not require that plenum cables have to be fire-retardant.

No doubt, there is a lot of cable inside plenums, but not all of it meets the safety standards for plenum-rated cable.

Much of that is due to the telecommunications boom of the 1990s, when office buildings installed new cable, on average, every three years, often putting new cable on top of existing cable. Plenum cable production grew at an average annual rate of 46 per cent between 1991 and 1998.

Today, for example, in the U.S. there is an estimated 45 billion feet of cable housed in plenums – much of it abandoned. No one disagrees that a critical mass of cable poses a fire hazard.

What is disputed, however, is how much cable is excessive. Simply put, the equation can be reduced to the following: The amount of smoke produced in the plenum is directly proportional to the fire-load in it.


Taking heed of such dangers, the National Fire Protection Association, or NFPA, one of the world’s leading fire-safety bodies, updated two standards that form the heart of all telecom standards:

NFPA 70: National Electrical Code Handbook (2002).

NFPA 90A: Installation of Air Conditioning and Ventilating Systems (2002).

In the section that applies to combustibles in plenums, the technical committee clearly delineates what manufacturers and building owners now face. In Article 725 of NFPA 90A, a 31/2-page section, the technical committee agreed that excessive cable in ducts and plenums posed a fire hazard, essentially acting as fuel load.

Although plenum cables are not typically the ignition source of fires, due to the low energy conducted through them, a critical mass of abandoned cable will add to the heat and energy released in a large fire.

Consequently, after much debate and fiddling with the language, NFPA concluded the following:

Abandoned cable in ducts, plenums and other spaces used for environmental air shall not be permitted to remain;

Excessive accumulations of abandoned cables in ducts, plenums and other space used for environmental air shall be removed, where practicable.

How will this be accomplished? According to NFPA 70, “The contractor will remove the old cable before installing the new system.” The code goes on to say that the result will be that “many BICSI members will [specify] abandoned cable removal within the scope of the installation of new communications and data systems.”

As to enforcement, that’s a local municipal concern, says Jeff Sargent, part of the electrical engineering group of NFPA in Quincy, Mass. “How the code is administered in the field is left to the local fire commissioners. I can’t say how it will be done,” Sargent says. “Yet, I haven’t heard many complaints about the new provisions of the code.”

Even so, a small but vocal minority of people within the industry say that the standards designed to protect the public have inherent weaknesses, placing people at risk.

“If a fire happens in an office building that has cabling up in the ceiling, workers are in peril – and it doesn’t have to be that way,” says John Michlovic, national marketing and technical manager with H.H. Robertson Floor Systems of Pittsburgh, Pa., makers of in-floor raceway systems for cable.

Here’s why. In 1975, the cabling industry petitioned NFPA for relief from stringent requirements imposed on them in NFPA 90A. After a series of meetings, NFPA allowed combustible cables to be used, on a limited basis.

“However, the limited use provision was never written into the standard,” Michlovic says. “And CMP cables, which met much less stringent criteria, became the standard of the cabling industry.” (See the Sept/Oct 2002 edition of Cabling Systems.)


Simply put, what the code writers might have intended in 1975, namely that combustible cables could be installed to a limited degree to address the telecom boom, proves the rule of unintended consequences: Today, plenums contain a critical mass of combustible cable.

“The standard was so relaxed that almost any junk cable can meet its testing criteria,” Michlovic says, referring to the steady flow of cable from Southeast Asia, where testing is generally lax.

Even testing methods like NFPA 262, which apply to environmental air plenums, don’t go far enough in mimicking real-life conditions. For one, it doesn’t apply to the cable installed years, if not decades ago. The fire-retardant properties of cable generally deteriorate after years of use, Michlovic points out.

“In most office buildings there is a lot of older cable, yet all testing is done on new cable with sound fire-retardant jacketing. “

Simply put, Michlovic’s argues against placing any cable in plenums, unless it’s limited combustible. “Plenum cables are a dangerous fuel load. A pound of plastics has a fuel load similar to a pound of gasoline.”

Not exactly, says Gary Lougheed, a senior scientist with National Research Council of Canada in Ottawa, who has been working on a study, Cable Fires in Plenums, since 2000. (Its lead sponsor is American Society of Heating, Refrigeration and Air-Conditioning Engineers, or ASHRAE.)

“That’s pretty much a generalization,” Lougheed points out. “The cables that are used and tested to standards [like NFPA 262] are not very flammable. Actually, they are very difficult to burn.” (see sidebar, Cable Testing)

Allowing cabling in a building is taken for granted today, but it’s really an exception to the building code. A model building would be built of concrete, glass and steel, and contain nothing else.

“That’s one of the things expressed in the National Electrical Code,” Lougheed notes. “It essentially s
ays that in a high-rise building, because of the time it takes people to get out of the building, one must limit the amount of combustible material in it.”

Still, Lougheed’s study, scheduled for publication at the end of this year, has yet reached a conclusion on what amount of cable in plenums is excessive. “That’s one of the areas that I’m trying to sort out,” he says.

Others like Michlovic hold little doubt on what went wrong. “NFPA inadvertently created the problem in 1975 by allowing the installation of combustible cable in ceilings.” That forms the core of the message that he has taken on the road, giving more than 40 presentations in the U.S. since last June to architects, building designers and life-safety engineers, encountering little resistance along the way. “If there were something wrong with what I am saying, surely after 40 presentations someone in my audience would have challenged it. Yet, I have never had that happen.”


If that’s not enough to make your blood pressure rise, there’s the problem of lead-containing plenum cables. One chief reason that plenum-approved cable is fire-retardant is that it’s made with polyvinyl chloride, or PVC, one of the most widely used insulating materials.

Among its advantages is that it resists flame, oil, ozone, sunlight and most solvents, and equally important, lead gives PVC excellent wet electrical properties.

In Canada, PVC is used in 60 per cent of all wire and cable, polyethylene in 34 per cent, and other resins make up the balance. Yet, PVC is the only plastic material that uses lead as a stabilizer. (And many argue that when PVC burns, the result is a lot of black smoke.) As well, lead is among the 743 chemicals listed in California as causing serious health problems. (See, Get the Lead Out)

Thus, manufacturers are turning to materials other than PVC. For example, fluorinated ethylene-propylene, or FEP, which meets the criteria for fire-retardancy. “FEP has exceptional dielectric properties in addition to excellent chemical inertness, heat resistance, weather resistance and toughness and flexibility,” reports Massachusetts Toxics Use Reduction Institute in Lowell, Mass. Teflon, a DuPont trademarked product, is one notable example of an FEP

One of the leading proponents of FEP, until recently, has been Frank Bisbee, editor of, an industry newsletter based in Jacksonville, Fla.

“FEP is a long-lasting, highly stable material that contains no lead and no phthalates,” Bisbee writes. “From a fire hazard perspective, PVC has a fuel load similar to gasoline, whereas FEP has a fuel load similar to concrete. The safe choice is clear.” (Phthalate is a plasticizer that is also considered toxic to humans.)

Yet, things quickly change. In April, Bisbee raised health and safety concerns about Teflon-based cable, which has been gaining market share in the U.S.

Currently, cable manufacturers are continuing to develop other formulations to displace lead as a stabilizer, yet the technologies are emerging and have yet to gain wide acceptance in Canada and the United States.

Among those working assiduously on the ultimate solution are Avaya Inc, TeknorApex, AlphaGary and Furukawa Electric, each having developed alternatives to lead as a stabilizer.

Equally important, some companies are looking to PVC-free wire and cable. For example, Environmental Canada reports that in Canada, XLPE technology is used in the NMD-90 residential building wire niche.

The winning formulation has to address both technical and environmental concerns, yet remain cost-competitive with existing technologies.

To be sure, the cabling sector has some tough choices to make, as it undergoes some changes. Chief among them is whether any more new cables ought to be crammed into plenums, thus adding to the fire load.

According to Michlovic, it would be safer to place cable in steel ducts in the floor, fireproof the underside and bury everything in concrete. “That’s much safer than cabling ceilings and putting wires through holes in the floor — methods that sacrifice safety.”



There are a number of tests to measure a cable’s flame retardancy, which measures its ability to stop burning once the source of heat is removed. They include UL 1581 (Vertical Tray Test, or IEEE 383) and UL 1666 (Riser Test). Plenum cables, however, have to pass the most stringent fire safety test: UL 910 (Steiner Tunnel Test), which is compatible with NFPA 262. In the test, a flame source is applied to a horizontally installed cable in a plenum environment for 20 minutes at a rate of 300,000 BTUs an hour. To pass the test, the flames must spread less than five feet and produce very little smoke.



Despite pressure from businesses, voters in California overwhelmingly approved Proposition 65 in November 1986. Its purpose is to address the growing public concern about exposure to toxic chemicals. Under the law, businesses are required to provide clear and reasonable warnings whether a product poses a health risk, thus empowering consumers to choose whether they want to use a particular product.

Each year, the state publishes a list of chemicals known to cause cancer, birth defects or other reproductive harm to females. Currently, the state lists 743 chemicals, including cadmium, antimony oxide and trioxide, which are widely used in cable manufacture.

The chief concern, however, is lead, reflected in the number of lawsuits that consumer groups have filed in California.

“Currently, there are about 30 consumer product manufacturers that have been sued for not labelling lead-bearing PVC components such as wire and plastic housings,” reports the Lowell, Mass.-based Massachusetts Toxics Use Reduction Institute (TURI) in its 2002 report, Environmental, Health and Safety Issues in the Coated Wire and Cable Industry.

In one lawsuit, the Mateel Environmental Justice Foundation successfully sued Microsoft Corp. in its marketing of PVC-coated wire and cable. As TURI says in its report, “A series of lab tests revealed a sufficient amount of lead leaching from the wire and cable and other PVC-lead products during wire handling to require Prop 65 labelling.” The case was settled, Microsoft paid a civil penalty of US$65,000, and had to either label its products or reformulate them to contain less than 300-ppm lead.

Despite claims by some scientists that the law does little to promote better health, it’s unlikely that the issue will go away soon. Frank Bisbee, editor of, compares the lead liability issue to what took place with asbestos in the U.S: “Insurance industry analysts and legal professions [are] predicting that lead liability settlements [will] cost the insurance industry well over $3 billion (US),” Bisbee points out.



In high concentration lead can cause brain damage, kidney damage and gastrointestinal disorders. Long-term exposure affects the blood, central nervous system, blood pressure, kidneys and the metabolism of vitamin D. In children it causes slowed cognitive development, reduced growth and other problems.

Perry J. Greenbaum is a writer based in Montreal and New Hampshire. He can be reached at