Specialist cable materials
Low smoke cables
In recent years, halogen-free cables have become popular as they offer significant safety advantages and also reduce damage to the environment. As this technology is now more widely used, many industry standards or industrial applications specify halogen-free cables.
Halogen-free cables distinguish themselves as the materials used are free from chlorine, fluorine, bromine and iodine. Fluorine and chlorine are used in plastic molecules such as fluoroplastic or PVC (polyvinylchloride), whereas bromine is used in flame retardants. It is however necessary to understand that halogen-free allows minimum amounts of chlorine and fluorine. A cable is called halogen-free if less than 0.2 % chlorine and less than 0.1 % fluorine are used. Halogen-free materials are classified according to DIN VDE 0472.
In the event of a fire, traditional PVC cables burn with a thick toxic black smoke containing hydrochloric acid. This smoke is dangerous when inhaled, reduces visibility considerably and is corrosive. In contrast, halogen-free cables only give off faint smoke which is less toxic and is not corrosive, significantly reducing the damage to computer storage media such as hard disk drives where data can be destroyed by thick smoke.
While the driving force for halogen-free is primarily safety, cables manufactured without the use of PVC and phthalate (softeners) cause less harm to the environment. The disposal of halogen-free cables also does not cause problems. When the metallic cores have been removed, the plastic can be recycled or disposed of safely.
Low smoke zero / free of halogen
Halogen-free cables should not be mixed with the term "low smoke zero halogen" (LSZH) or "low smoke free of halogen" (LSOH). Halogenfree defines the behaviour of the cable material in case of fire or the flammability. 'Low smoke' requires that little smoke is produced. 'Zero halogen' requires that no halogen is released and no corrosive or etching acids are released. Low smoke zero halogen is becoming very popular and, in some cases, a requirement where the protection of people and equipment from toxic and corrosive gas is critical, for example in the railway industry.