Why we need LSZH Fiber Cable
The clearest uses for LSZH are confined spaces with large amounts of cables in close proximity to humans or sensitive electronic equipment. Submarines and ships are classic examples, which is why the military was one of the first adopters of LSZH standards. Additionally, mass transit and central office facilities are common applications for LSZH, and many telecommunication standards require LSZH cables. The use of LSZH cables in Europe has been widespread since the 1980s. It has never achieved such widespread acceptance in the United States, primarily for cost reasons, but also because of performance concerns. Some of the cable designs used in Europe cannot pass U.S. test standards, and the high additive loading needed to pass the U.S. flame tests can lead to reduced physical properties if not done carefully.
Installation at lower temperatures can also be affected. Reduced flexibility due to the high additive loading in the materials can prevent cables from being installed in cold environments. The high mineral content can also result in fractures of the material if the installation is not done carefully. Research of the cracking behavior of LSZH has been done with the goal of improving performance [9].
One advantage of LSZH is that it typically has a lower coefficient of friction, although lubricant suppliers recommend a special pulling lubricant for low-smoke, zero-halogen jackets [5]. Though there has been a trend toward jackets that do not require lubrication, some installations will still require lube to help with difficult pulls.
There are still questions about the necessity for LSZH cable in some applications. Fires are dangerous, but so is electricity, and if a higher voltage or mission-critical cable is more likely to be damaged during installation or from physical or chemical damage during its lifetime, this could conceivably result in a statistically more dangerous product than a halogenated cable.
Another consideration is the environment in which the cable will be installed. If a fire occurs in an open area in which smoke concentration is not sufficient to obscure escape routes, using a LSZH cable may not be beneficial. There is also the question of the fuel load in a building other than cabling. The smoke being given off by other materials burning can vastly outweigh the contribution of the wire and cable. Of course, this is highly dependent on the installation and the relative amounts of cable present as well as the building’s function and contents. However, there is no question that the amount of cable installed in buildings has increased as data communication has proliferated. Central office telecommunication facilities were some of the first places that LSZH cables became common due to the large relative fuel load represented by wire and cable.
Modern data centers contain large amounts of cabling, and are usually enclosed spaces with cooling systems that can potentially disperse combustion byproducts through a large area. In industrial facilities, the relative fuel load of cables will not be at the same level. Other materials burning may also contribute greater amounts of dangerous gases that outweigh the effect of the cables. There have been notable fires where cables burning contributed to corrosion (the Hinsdale Central Office fire is a famous example), but in some instances, better fire response techniques could have prevented this damage. The nuclear industry is another area where LSZH cables have been and will be used in the future. Major cable manufacturers have been producing LSZH cables for nuclear facilities since the early 1990s. The expected construction of new nuclear plants in the U.S. in coming years will almost certainly involve some LSZH cable.
One of the most important things to understand about LSZH cable (and of course cable in general) is that no two products are the same and that there are many factors that will define the suitability of the final product to its application. In fact, research done by a major pulling lubricant supplier tested 27 LSZH compounds and found a huge variation in physical properties. So even using material that meets the base requirements of one of the many specifications available may not result in the best material for the application. Understanding the goals, results and limits of these tests are key to finding the right product. In any case, the trend to consider environmental concerns with a greater weight relative to performance has increased and it can be generally stated that there is an enlarging market for cable that can be demonstrated to be environmentally friendly.
