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Cabling for Safe Schools

SAFE SCHOOLS

Cabling your school computer networks for the information age...?

Note:  Toxic Gases were not measured in these tests.

The fire performance of computer network cables is crucial. Here is information you need to help keep your schools fire-safe.


Specifying The Right Data Cable

When you're installing computer networks to prepare your schools for the information age, you face a range of decisions about equipment, software and cost. One good way to help assure performance and safety is to select the right data cable.

CAT 5 is the current industry standard cable for computer networks. Because this cable is endorsed by computer equipment suppliers and system designers for data network applications, your cabling contractor should use CAT 5 plenum cable.

CAT 5 cable is available in non-plenum and plenum grades. Both grades meet the same electrical requirements for high-speed data communications. However, only the plenum grade is rated to provide the low flame-spread and low smoke safety performance that building codes require for cables used in air-handling spaces.

It's Not Enough To Simply Specify "CAT 5 Plenum" Cable

As cabling professionals, we think you should know that not all CAT 5 plenum cables are the same. That's because some cable manufacturers use whatever materials will allow them to meet minimum requirements for fire safety performance.

The industry standard CAT 5 plenum cable is shown in Figure 1. Cable manufacturers use PVC (polyvinylchloride) with flame-retardant additives as the outer jacket. The insulation on each individual wire is FEP (fluorinated ethylene propylene), the most widely used insulation material since plenum cable was introduced in 1976. (FEP is also known as Teflon®, a DuPont trademark.) However, some manufacturers have recently started to substitute insulations in place of FEP.

Figure 1


Industry and regulatory agencies are taking steps to improve testing procedures because of concerns about fire test results with these insulations.

Avoid High Fuel-Load

A recent technical paper by fire science experts from Lucent Technologies, BICC Brand-Rex and DuPont reports some disturbing facts about the fire performance of high fuel-load insulations such as polyethylene, when used in European cables designs. Fire tests conducted in the United Kingdom (UK) are discussed in the paper, "Full-Scale UK Fire Tests of LAN Data Communications Cables Used in Concealed-Space Applications", which is provided for reference.

As shown in Figure 2, the fuel-load of polyethylene approaches the fuel-load of gasoline, and can contribute nearly ten times more fuel value than FEP in a fire situation. This explains why FEP is the preferred insulation material for fire-safe data cables. It should be noted however that fire performance testing is conducted on finished cable, not material and that U.S. cable designs are different and must meet more stringent requirements.

Figure 2


A second paper, "Comparison of Communications LAN Cable Smoke Corrosivity by US and IEC Test Methods", co-authored by Lucent Technologies, Underwriters Laboratories and DuPont, provides information about smoke damage. Simply put, the paper suggests that combustion products from plenum cables are less likely to damage electronic circuitry than combustion products from other cables. In short, plenum cables insulated with FEP should provide the most protection for digital equipment in fire situations.

The Solution

Specifying plenum cable with FEP insulation is one sure way to head off potential problems with fire safety. By using the cable specification endorsed by ACP, "High Speed LAN Communications Plenum Cable", available on this website, school networks will get both the excellent fire and electrical performance of FEP insulation. We recommend that you specify, and accept nothing less than, 100% FEP insulation.

 

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  Friday, July 18, 2003
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