Flame Retardancy in Halogen-Free Cables

Halogen-free cables are a required staple in a vast number of industrial and infrastructural applications. Over time, different labels for these cables have been established, such as FRNC, HFFR, LS0H, or LSZH. But how meaningful are these abbreviations, and what are the benefits of halogen-free cables compared to products containing halogens? Let HELUKABEL explain.

Flame retardancy in halogen-free cables

What are halogens?

Halogens are a group of chemical elements that include fluorine, chlorine, bromine, and iodine. These substances are often used in various types of plastic materials, including those used to manufacture cables, such as PVC (polyvinyl chloride). Halogenated materials have been popular in the cable industry due to their cost-effectiveness, durability, and chemical resistance. A cable is considered halogen-free if its insulation and sheath materials do not contain halogens such as chlorine, fluorine, or bromine.

Halogen-Containing PlasticsHalogen-Free Plastics
Chloroprene rubberSilicone rubber
Fluoroethylene propylene (FEP)Polyurethane
Fluoropolymer rubberPolyethylene
Polyvinyl chloride (PVC)Polyamide
 Polypropylene
 Thermoplastic elastomers

Why are halogens harmful?

Halogens pose significant health risks, particularly when halogenated plastics like PVC catch fire. During a fire, hydrogen halides are released from the plastic, which can react with moisture—whether from firefighting efforts or humidity—to form acids. Chlorine converts to hydrochloric acid, while fluorine can produce highly corrosive hydrofluoric acid. Additionally, combustion can generate hazardous byproducts such as dioxins and other toxic chemicals, which can cause severe respiratory damage upon inhalation and potentially lead to death by suffocation. Survivors of such incidents may also face long-term health issues.

Key Risks Associated with Halogens:

  • Toxic Gases: The combustion of halogenated materials emits toxic gases, including hydrochloric and hydrofluoric acid, which can severely damage the respiratory system.
  • Dioxins and Toxic Byproducts: Burning halogenated substances can produce dioxins, which are linked to long-term health effects like cancer. These toxic compounds can accumulate in the environment and food chain.
  • Environmental Impact: Halogens, especially chlorine and bromine, contribute to ozone layer depletion, increasing UV radiation exposure on Earth and raising the risk of skin cancer and other health problems.

By opting for halogen-free cables, these risks can be mitigated. Halogen-free cables are designed to be both safe and environmentally friendly, making them an ideal choice for modern installations. Investing in halogen-free solutions helps protect both people and the environment while ensuring compliance with strict safety standards.

Where are halogen-free cables used?

Halogen-free cables and wires are required, for example, in buildings where people gather and where valuable material assets must be protected. Examples for this are:

  • Building technology: In public buildings such as offices, shopping centres, schools, hospitals, and airports, strong fire and health risk prevention ordinances are in place. Most of the cables and wires in these places are fixed in their installation and do not need to fulfil any special chemical or mechanical requirements. PE or PP-based plastic mixtures are often used here, which are halogen free and flame retardant, and produce little smoke or toxic gas. They must also often pass bundle burning tests.
  • Industrial automation: Machines and plants often require cables and wires with high chemical and mechanical resistances. When used in flexible applications such as in drag chains or in robotics, these loads are especially high. Typically, sheath mixtures based on TPE-O or TPE-U (PUR or Santoprene) are used here. These are also available with halogen-free constructions but are not able to be manufactured to be as flame retardant or low smoke as cables for building technology.

What labels and designations should I look for to find halogen-free cables?

Over the years, different manufacturers, markets, regions, and standards have developed different labels for halogen-free and flame-retardant cables:

  • FRNC - Flame Retardant and Non-Corrosive
  • HFFR - Halogen-Free and Flame Retardant
  • LS0H - Low Smoke and 0 Halogen (also known as LSOH)
  • LSZH - Low Smoke and Zero Halogen

None of these labels, however, deliver concrete information regarding flame retardancy, corrosiveness, toxicity, and light attenuation. Users must therefore pay close attention to the standards listed in the data sheets of each supplier. The information listed there is the only way to identify the flammability properties of a cable (horizontal, vertical, or bundle burning tests).

Which Standards are Typical for Halogen-Free Cables?

  • DIN EN 60754-1 VDE 0482-754-1:2021-02 defines the testing machines and the testing procedures required to identify the total acidity. The test result must show values lower than 5mg/g to be certified as halogen free.
  • DIN EN 60754-2 VDE 0482-754-2:2021-02 defines the measurement of the pH value and conductivity. The test result for the pH value must be below 4.3 and for conductivity, it must be under 10µS/mm.
  • DIN EN 61034-2 VDE 0482-1034-2:2021-02 defines the measurement of smoke gas density of burning cables. The test result must show a light attenuation of no more than 40% to be considered low smoke. Depending on the application, customer, and region, lower light attenuation can be required. The goal is for people to be able to still recognise the source of the fire, as well as possible escape routes. These standards are required in public buildings and trains due to the high density of people present.

Take Away

In many applications where safety is critical, halogen-free cables and wires offer substantial advantages, as less toxic gas and smoke is emitted in the case of a fire. At the same time, these products must exhibit high flame retardancy in order to comply with different standards and requirements. It is not enough to rely on the common labels of FRNC, HFFR, LS0H, or LSZH to determine the actual flame retardancy of a cable. The standards named in data sheets are the only information you should rely on. It is through these standards that users can determine whether the product is considered to have low, middle, or high flame retardancy, if they are constructed to be low smoke, or if they have been tested for light attenuation. As experts for electrical connection technology with more than 45 years of experience, HELUKABEL is happy to help you identify the most ideal cables and wires for your application.

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