Here is the "dull dry article" Rayelan wrote about:
And here is the "strange pairing" of Credit Lyonaisse and Rockefeller Center.
"The potential for serious fires is all around us. Although communications cabling was not implicated in the Dusseldorf, Credit Lyonaisse or Rockefeller Center fires, it could have been."
If you scan the article, you will agree with Rayelan, the above sentence is REALLY out of place. I wonder if the author was sending someone a message?
FIRE SAFETY:
Does Your Category 5 Cable Measure Up?
An Introduction by Dr. Stephen C. Paulov,
Editor - Cabling Business Magazine
http://www.wireville.com/headline/firesaft.htm
CBM has learned that Underwriters Laboratories (UL) has issued a formal letter to convene a technical advisory panel to address concerns over qualification and follow-up test programs for Communications Plenum (CMP) and other plenum-rated cables.
The letter states that "testing programs and methods of ensuring continuing compliance with listing requirements are not producing the desired result." When it comes to life safety this an alarming statement.
"Fire Safety: Does Your Category 5 Cable Measure Up?" presents a new concept in fire safety margin (headroom) of plenum-rated Category 5 cable for cabling system designers and end users to consider.
In order to be listed as Multipurpose Plenum (MPP) or CMP, and to qualify for installation in air-return plenums, cables must pass the flame-spread and smoke-density requirements of UL 910 (one of the most stringent fire tests in the world). This raises an interesting question. Is a simple pass/fail criteria good enough, or is there a comfortable passing margin that means better fire protection and more peace of mind? This could become a difinitive issue which may bring our industry to another milestone on the journey to the ultimate cabling system.
It's too early to know the market's response and acceptance of the concept of fire safety headroom. Certainly there will be strong opinions both for and against. Some will undoubtedly see this issue as more marketing hype. But, before dismissing fire safety margins as another marketing ploy, consider the following issues:
Electrical performance headroom of Category 5 cable has become a legitimate criteria in the design of high - performance cabling systems and has led many cable manufacturers to produce an enhanced Category 5 cable. The fact of the matter is that enhanced Category 5 products are capturing a growing share of the market. Yes, we have codes, standards and specifications, but, who says we can't build, design and install technology that's even better? Will this also hold true for fire safety? And, is it a logical correlation to electrical headroom?
Who hasn't removed ceiling tiles and exposed large amounts of abandoned, unused cable in plenum areas? Considering the many generations of cable packed into air return plenums, fuel load build-up from cable jacket and insulation materials is a real threat.
The potential for serious fires is all around us. Although communications cabling was not implicated in the Dusseldorf, Credit Lyonaisse or Rockefeller Center fires, it could have been. Through National Fire Protection Agency and National Electrical Code, the United States has made tremendous strides in reducing the risk of fire from telecommunications cabling. Some end users and building owners simply want the best protection and technology, and accept the associated costs which are minimal compared to the potential consequences.
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by Stephen Martin
The market demand for Category 5 plenum-rated cables far exceeds that of similar cables for nonplenum applications. The demand for these cables is driven by the ease of installation in plenum-designated pathways, without the need to first install metallic plenum-rated conduits. With the recent introduction of insulation substitutes for FEP, the question at hand is, are cable system designers and end users assured that the cable they specify will comfortably meet low flame spread and smoke regulations? Not all Category 5 cables have the same margin of safety or fire safety headroom.
Today, building codes for many municipalities follow the National Electric Code (NEC) guidelines for selecting cables. The NEC is written and maintained by the National Fire Protection Association (NFPA). This organization sets guidelines and standards for fire safety as they relate to the proper cable selection for communication applications. For plenum communications cable, the listing of CMP (Communications Plenum) or MPP (Multipurpose Plenum) must be established by independent testing per Underwriters Laboratories (UL) 910 and UL 944. And more cable is being installed today than ever before. Furthermore, the old decommissioned legacy cable is often left in place, continually increasing the amount of combustibles in concealed spaces. The UL 910 test, often called the Steiner Tunnel Test, evaluates the flame spread and smoke emmission characteristics of cables such as plenum-rated Category 5 Unshielded Twisted Pair (UTP) cables. The flame-spread and smoke-optical density results are compared to required limits. The listing of a cable as CMP MPP is only awarded after the cable has exhibited low-flame spread and smoke density attributes, according to the UL 910 specifications.
Engineers developing high-performance Category 5 UTP cables use the TIA/EIA 568A guidelines for electrical cable performance and basic construction parameters. The TIA/EIA document includes recommendations for cable network topology, cable and connector media options and component and system link performance recommendations. There are also general guidelines for Category 5 cable construction. The construction guidelines consider the minimum and maximum conductor size, conductor insulation diameter and overall cable diameter limits. There is, however, an intentional omission of actual material selection requirements for fabricating the cables. The material selection for designing Category 5 cables, specifically the insulating plastics for plenum and nonplenum applications, is left to the manufacturer to choose. The cable design engineer's task is to create a high-performance cable that meets not only the electrical requirements of Category 5, but also the fire safety requirements required for plenum and nonplenum cables as defined by the NEC guidelines.
Flame spread characteristics are attributed to various elements of the cable design. Cable geometry, conductor insulation material, cable jacket material and thickness all play a role in limiting flame spread when a cable is burned. Most plenum rated Category 5 UTP four-pair cable, up until a few years ago, possessed significant fire performance margins versus the pass/fail requirements. However, a trend has gained momentum in the cable design and manufacturing community in recent years to develop cables that use reduced amounts of low dielectric, high-fire performance, low fuel load fluoropolymers, specifically Fluorinated Ethylene Polyethylene (FEP) thermoplastic.
Historically, the use of FEP has been preferred by cable designers because of its inherent low-smoke generation and low flame spread characteristics and excellent dielectric properties. In recent years, due to the increased demand for Category 5 UTP cables, the supply of FEP has lagged behind cable production needs. As a result, significant research has been conducted by scientists and cable design engineers to develop a non-FEP material (or compound) that would just meet the electrical and flame resistance demand for plenum-rated Category 5 UTP cables.
A cable systems' designer should consider electrical characteristics and margins of performance when evaluating Category 5 cables and to evaluate the fire safety for the cable under consideration for plenum installation. Using cables tested and designated as CMP or MPP, suitable for use in plenum installations, is the first step in the safety evaluation of cables. Some plenum-rated cables, based on their construction and material composition have varying safety margins, relative to the UL 910 pass/fail limits for fire spread and smoke emission.
Currently, many manufacturers of plenum-rated Category 5 cable offer these products with reduced amounts of FEP. The basic design concept has been to substitute the use of FEP on one or two of the pairs with a highly flame-retardant olefin-based material. The result is a Category 5 cable with a composite core construction, generally referred to as a "2x2" construction - two pairs using FEP and two pairs using the flame retardant ployolefin.
Currently, much effort is being expended to improve the fire resistance characteristics of the 2x2 design. Flame spread tests performed according to the UL 910 test show that the 2x2 design, in many cases, meets the flame spread and smoke emission requirements. These results must be considered marginal. Therein lies the concern from network cable system designers and building owners as well. This phenomenon can be considered to be a "fire performance headroom" issue.
The cable system design community must be aware of this large difference in fire safety between the all-FEP Category 5 cable and the 2x2 alternative. This discussion is not asserting that the testing agencies, such as UL or ETL Testing Laboratories, are unaware of this issue. In fact, UL and ETL have been active in assuring the industry that current 2x2 designs meet the stringent UL 910 test. However, most in the industry would agree that fire safety margins are less than that of the all-FEP design.
There may very well come the day when, through diligent research, 2x2 or non-FEP Category 5 UTP designs become commonplace and achieve the same safety performance as the all-FEP designs. That day has not yet arrived. There is no doubt in the cable manufacturing industry that the all-FEP plenum design is superior, not only in electrical performance, but also in fire safety specifications. With the increase in availability of FEP for Category 5 UTP cables, logic would indicate that specifiers of Category 5 UTP cables seriously consider using all-FEP cable constructions. Not only will the end user be assured of the highest quality cable for system transmission, they will also receive the best cable construction for for fire safety. This is especially important since many generations of cable can accumulate in plenum spaces.
Before system designers and end users accept the use of a 2x2 design in their network, they should consider the possible compromises to flame safety margins. They must be aware of this issue in order to make an educated decision in the final selection of the product as it relates to workplace safety today and in the future.
Stephen Martin
Stephen Martin can be contacted at Berk-Tek, 954-704-7873
: Rayelan sent me an email in which she stated that a reader
: had had sent her an article on "fire safety" in
: response to the RMNews article on TWA800.
: In the article posted by RMNEWS, it was stated that the reason
: TWA800 was downed was because millions of bogus bearer
: bonds were on board. If they had been exposed as frauds,
: the Federal Reserve Banks that owned them would have
: collapsed.
: http://www.rumormillnews.net/cgi-bin/config.pl?read=8572
: This is an excerpt from that article: "Banks in France
: have also discovered that they hold
: counterfeit bonds. But they didn't kill anyone to destroy
: them, they merely set a fire that gutted the entire third
: floor
: of Credit Lyonaisse in Paris. Presumably that is where they
: stored their phony bonds.
: "Every institution chose their own way of handling the
: "bad
: paper" crisis. Too bad a few more fires couldn't have
: been
: started. A lot of good people would still be alive."
: Rayelan said someone sent her an article on fire safety in
: which the Credit Lyonnaise fire was compared with a fire at
: the Rockefeller center. She said she couldn't find the
: article when she went to retrieve it.
: Here is her comment: "When I read the article, it was a
: dull dry article on fire safety, then there was a sentence
: that popped out at me because it was really were out of
: place. The sentence mentioned the fires at Credit Lyonaisse
: and Rockefeller Center.
: "I thought the 'pairing' of the two said more than
: anything! In fact, I have the feeling that the 'fire
: inspectors' and those with inside knowledge of fires, were
: trying to tell us something."
: If you happen to be the one who sent her the article, can you
: send it again?
: thanks,
: Jack
