Halogen free cable is the classification of wire sheaths in the wire and cable industry. Low smoke zero halogen cable (LSZH) sheath is thermoplastic, when the cable sheath temperature is too high and cause of fire. Halogen wire sheath does not contain halogens and has a high flame retardant rating, making it difficult to burn.
Most cable coverings are made of polyethylene and PVC. In the event of a fire, plastics containing chlorine will release toxic hydrogen chloride and, when exposed to water, will produce hydrochloric acid. Low smoke and halogen free cables do not release hydrogen halides or other acids when they catch fire.
Halogen Free cable Standards
The DIN EN 61034 standard describes measuring the smoke density of burning halogen cables under defined conditions. The smoke density of cables and wires is expressed in minimum values for the light permeability. Fire safety calculations can be derived from the standard.
DIN EN 61034-2 standard makes recommendations for the event that there are no requirements in other standards. This annex recommends a light permeability value of 60% as the minimum value.
Therefore, ZW Cable products that comply with the DIN EN 61034 standard guarantee a light permeability of at least 60% according to the test method described.
Some common names for halogen free cable markings have emerged in the cable industry.
|FRZHF||Fire Retardant, Zero Halogen|
|FRNC||Flame retardant, Non-Corrosive|
|LSNH||Low Smoke, Non-Halogen|
|LSHF||Low Smoke, Halogen Free|
|LSOF||Low smoke, Zero Halogen|
|LSZH||Low smoke, Zero Halogen|
Why use halogen-free cable?
In the event of a fire, halogen-free cables do not produce harmful, corrosive fumes. Therefore, low smoke and halogen-free insulations are often utilized in ships, trains and large buildings. Halogen free flame retardant cables are also commonly used in the railroad industry because there are high-voltage lines underneath the railroad or signal lines that transmit the train’s location.In cable industry, we call it railway cable.
Using halogen free wires also reduces the accumulation of toxic gases when the line is damaged by fire.
The main reason why most people use low-smoke and halogen-free cable are to protect themselves from toxic fumes. Halogen compounds release toxic fumes when they burn, leading to severe respiratory problems or even death if not properly treated. Another reason many people choose halogen free cables is that they have a lower melting point than other types of wires.
In addition to being safer for use in certain environments, halogen-free cables are also more environmentally friendly than their counterparts with halogens. They do not contain chlorine or bromine, meaning they will not contribute to ozone layer depletion if released into the atmosphere. They are also less toxic than other cables, so fewer harmful chemicals will leak out into your environment if there is a break in one of these cables.
Halogen free cable advantages
Halogen free cable is less susceptible to fire propagation because they contain no halogens. These substances are used in conventional halogen cables as fire retardants. In case of fire, they react with water and form corrosive gases, which can cause explosions and heat the cable conductor and insulation. The corrosion byproducts can also cause health problems for people who inhale them.
The additional advantage is that the chemical compounds used in halogen-free cables have a low caloric load, which means that they need less energy to heat up to ignition temperature than conventional cables. It leads to longer electrical functionality under the flame influence.
In addition, the unique properties of halogen free wire makes them suitable for emergency services for up to 180 minutes at temperatures up to 800°C (temperature class F). An additional special quality test guarantees the insulation integrity at this temperature after every extrusion process, where we put the cable through one of our temperature chambers at 800°C
Choosing the right halogen free cable
With all the rules, specifications, and different regulations and standards, it can be difficult for cable manufacturers to determine if they are meeting the LSZH rating adequately. Some specifications seem to meet these requirements, but surprisingly, they often do not explicitly state this but only provide information about the cable construction (mainly the jacket)
Other manufacturers, however, hide this information in certain places in their specifications, which may change if more engineers request these characteristics. If you are interested in purchasing halogen free cable but the manufacturer does not explicitly specify the fire characteristics of the product, it is best to contact the manufacturers.
It would be best to compare multiple halogen free power cable manufacturers to select cables with superior pvc halogen free features and then compare their flexibility, temperature range, bend radius, service life, and other key specifications. The final selection should have excellent fire resistance and minimal functional differences from PVC cable.