Halogen is a nonmetallic elements such as fluorine, chlorine, iodine or bromine. It is generally used as flame inhibitors in many plastics, including PVC that goes into cable insulation and electronic products. Halogens are a group of chemical elements including iodine, bromine, fluorine, astatine, and chlorine. When these elements are exposed to fire, they form hazardous gases which are harmful to harm the eyes, nose, lungs, and throat.
LSZH is a material category used to classify cable insulation. LSZH (Low Smoke Zero Halogen) cable insulation is made of materials designed to give of reduced smoke and no halogen when exposed to fire. When combined with other fire deterrents and control practices, Zero Halogen Cables can help reduce fire related casualties and property destruction. These cables will also don’t give off hazardous gas/acids or toxic smoke when exposed to fire.
LSZH cables decrease the extent of smoke produced through fire and is normally used in inadequately ventilated areas, for instance, airplane and some areas that people may be affected by smoke and toxic fumes.
Beside the halogen free features, LSZH cable also has lighter weight, this is convenient especially if the cables are run overhead in a dropped ceiling. At the same time, the impact of halogen free cables will also be lower if there is a fire because there are fewer toxic chemicals involved.
Many different Fiber Optic Cable suppliers are now making low-smoke, zero-halogen cables. And it is currently widely used in Europe and elsewhere in the world contains halogens. The European market is demanding that cables used in LANs. WANs, etc. Meet LSZH specification. The IEC 60332-1 governs the Flame Retardant Grade specifications in reference to LSZH cable.
Essentially the compound used in manufacturing cables meeting the above specifications reduces the amount of dangerous/poisonous gases in case of fire. The main difference in specifications between IEC 60332-1 versus UL 5181, UL 1666 and UL 910 is that the cable under the IEC specifications continue to burn while still emitting very low gases. UL specs demand that the flame be extinguished, but it can still be emit poisonous/dangerous gases.
Most safety advocates are calling for the used of LSZH cables, especially for the plenum space. Review your local building codes to determine if you must use LSZH cable. Non-LSZH cables will produce corrosive acids if they are exposed to water when burned; such acids may theoretically further endanger equipment.