Difference Between PVC cable, Low Smoke Cable(LS) & Low Smoke Zero Halogen Cable(LSHF)


Because of the absence of standardization and a lack of understanding, 

there is plenty of confusion and misunderstanding about definitions of cables when choosing a Cable. 

They are classified as “LSF / LS” (Low Smoke), “LSZH / LSHF (Low Smoke Zero Halogen), “FR” (Fire Retardant), “FR” (Fire Resistance) “, FRLS” (fire-resistant Low Smoke), “FRLSZH” (Fire retardant Halogen-Free).

types of cables

Types Of Rated Cables

Cable / Wire Terminology

  • Based on the kind of insulation material on the wire, it is possible to categorize cables and wires into three main categories: PVC, Zero Halogen and Fire Retardant.
  • We are generally classified into two kinds of categories based on the application.

Non-Fire Rated Cable

  1. PVC = Polyvinyl Chloride
  2. LS / LSF = Low Smoke / Low Smoke Fume
  3. LSHF / LSZH / LSNH = Low Smoke Halogen Free / Low Smoke Zero (No) Halogen
  4. LH / HF = Low Halogen / Halogen Free

Fire Rated Cable

  1. FR =Fire Retardant
  2. FR =Fire Resistance
  3. FRLS = Fire Resistant, Low Smoke
  4. FRLSH = Fire Resistant Low Smoke and low halogen
  5. The acronym FRLSZH/NHFR/ZHFR and HFFR are Fire retardants. Lower Smoke Zero Halogen Non (Zero) Halogen-Free, Fire retardant
  6. HRFR=Heat Resistance Fire Retardant

PVC, FRLS, and FP cables have conductors and insulation to control the voltage and electrical current. They also come with physical protections, such as steel wire armour.The FRLSH and PVC cables differ in insulation materials surrounding conductors to suit different purposes and performance.

The qualities that distinguish one insulation electrical from the other

  1. dielectric strength or break down voltage
  2. maximum permissible temperature
  3. dielectric loss
  4. permittivity as well as some other properties that are appropriate for the particular application.
  5. The FRLS or FRLF quality of the insulating material. It may be PVC or XLPE.

Non-Fire Rated Cable

PVC Cable:

House wiring cable and wires

The PVC (Polyvinyl Chloride) cables usually comprise a PVC-based compound that serves as an insulating material.

PVC insulation is rated at an upper-temperature limit of around 70degC. From the temperature at which it is safest to use, it falls into the insulation with the lowest grade. Still, it serves its purpose since the power ratings and voltages involved are comparatively low.

When burning PVC cable, fire produces dense black smoke and produces a large quantity of toxic gas and hazardous chemicals.

Smoke Generated from PVC Cable Fire:

  • The burning PVC has decreased the region’s visibility up to 50 percent in just 10 minutes. Within 30 minutes of burning, the visibility could be decreased by up to 90%.
  • The reduced visibility can make it difficult to get out of the burning area or building.
  • The fumes and smoke generated by fire could be more harmful to the people around it and the flame itself.

Toxic Chemicals generated from PVC cable burning:

  • The burning of PVC generates a range of toxic chemicals. However, the most harmful one is hydrochloride (HCI). 
  • PVC releases around 28 percent of Hydrogen Chloride (HCI).
  • In its natural condition, HCL is a sour gas, almost colourless, that forms cloudy white vapours when it comes into air contact.
  • In addition, when mixed with water, it alters its state to create Hydrochloric Acid in any form, be it in a gaseous, vaporized, or liquid state; it’s a highly poisonous and corrosive material.
  • There are many negative adverse effects HCl could have on an individual. When inhaled, the lining of the throat could be affected enough that it becomes swollen, which can make breathing very difficult.
  • Contact with the eyes may cause everything from extreme irritation to permanent damage to the corneas. Like the mouth, mucous membranes can be burnt or even damaged, with severity based on HCl’s amount and exposure duration.
  • When you consider the cumulative consequences on someone from the smoke and HCl generated in the burning process, It’s difficult to discern, and victims are unconscious for a long time before the flames reach the victims.

Some extent Fire Retardant property of PVC Cable:

  • PVC is invulnerable to Fire ignition.
  • The PVC (polyvinyl chloride) is naturally Fire Retardant due to its chlorine base. It has a significant amount of chlorine ions within the molecular structure. They are challenging to break when exposed to temperatures.
  • If it should catch flame, PVC has a prolonged rate of spreading flame. PVC is among the lowest fire spread ratings, which means that it isn’t likely to aid in spreading the fire.
  • The temperature needed for the ignition of rigid PVC is over 150 deg Celsius higher than the required temperature to spark wood. 
  • The resistance to ignition of typical elastic PVC formulations is less; however, it can be substantially increased with unique formulations.
  • The fire inside the building is instantly snuffed out after removing the source of the fire.
  • PVC cables are bunched within the cable shaft or on the cable tray in the building or plant. In the event of a fire within these cables, the fire will become self-sustaining.
  • Additionally, because of the combustion of PVC, an intense corrosive fume is released, making firefighting very difficult due to the low visibility and the toxic nature of the smoke. The HCL content in the smoke can cause damage to the equipment that is more expensive and also penetrates the RCC and weakens its steel reinforced.
  • PVC include some Fire properties that are halogen resistant, although it can cause significant property damage and be hazardous for humans.

Advantage of Using PVC cable:

  • PVC is Cheap.
  • PVC provides greater flexibility and is sturdy
  • PVC has a reasonably long life span

Disadvantage of Using PVC cable:

  • When PVC cable is ignited, it releases a mix of chemicals and black smoke.

Application Of PVC Cable:

  • PVC cables are utilized to provide non-essential services that do not require performing in a fire.
  • Most of the time, it is used for domestic use, Office for general lighting.
  • They are great for low-risk buildings but usually not suitable for commercial or large public structures.

LS / LSF (Low Smoke & Fume) Cables:

  • LSF is also produced by using PVC compounds.
  • LSF cables are generally comprised of modified PVC compound (varying levels based on the manufacturer’s) that produces lower levels of HCI and less smoke when the burning process than PVC.
  • But, it produces between 15 and 22 percent (depending on the quality) of HCI gas, and due to its presence, PVC is still able to emit dense black smoke and HCl emission.
  • It is a halogen cable; therefore, it shouldn’t be mistaken for or similar to Low Smoke Halogen Free (LSHF) cables.
  • The quantity of PVC present in these cables may vary from manufacturer to manufacturer, making installing LSF cables in public areas challenging.

Advantage of Low Smoke Cable:

  • They are typically purchased to reduce costs or as a result of confusion in conjunction with LSHF cables.
  • They could be thought of as a slight enhancement compared to PVC cables.

DisAdvantage of Low Smoke Cable:

  • One should not use these cables for large commercial or public buildings, close to sensitive electronic equipment and in areas where escape is not possible in a fire.

Application of LS Cable:

  • Most commonly used for domestic, Office for general lighting.

LSHF / LSZH / LS0H (Low Smoke Halogen Free) Cables

  • LSHF cables consist of halogen-free substances that are effective fire-repellants yet emit less than 0.5 percent hydrogen chloride smoke and gas when burned.
  • In the event of a fire, LSHF cables only release tiny amounts of light grey smoke and small quantities of HCl, which increases the chances of escaping from a burning structure where it’s placed.
  • One reason LSHF products behave so differently when subjected to fire compared to the PVC & LSF cables is the total exclusion of PVC.
  • The outer sheath/Jacking and conductor insulation in these products are typically made of polyethene that is free of chlorine. Moreover, low levels of chlorine mean low HCl and non-toxic gas emissions.
  • It releases <0.5 percent of HCL gas. This provides an uninjured environment should there be a fire.
  • It’s not PVC in these cables, so there are no harmful fumes nor dense black smoke released in the event of a fire. This production ensures that evacuation routes and signs remain in view in an incident.
  • In some manufacturers, LSHF Cable, you can find the standard PVC cables over-sheathed by an LSHF jacket or cables with PVC insulation. If the jacket is burned and the PVC outer sheaths or insulation gives toxic gases, the same way PVC Cable.

Advantage of Low Smoke Halogen Free Cable:

  • LSHF cables are used in situations in which smoke emissions and toxic fumes can pose cause harm to the health of people and vital apparatus in the case of fire.

DisAdvantage of LSZH Cable:

  • Costly compared with PVC and LSF
  • Not as flexible as PVC

Application of LSZH Cable:

  • Because of their low level of smoke and toxicity advantages, LSHF cables are often used in various Public places, Non / Poor Ventilated Environments and essential applications.
  • Public space, buildings like Railway Stations, subway stations, cars, buses, bus stops, airports and planes, Carrier Ships, and other mass transit facilities.
  • A public underground or poorly ventilated place like subways, elevators
  • Sports and entertainment facilities for the public.
  • Hotels and apartment buildings
  • Hospitals
  • Computer/data centres

The differential between PVC Vs LSF and LSZH

  • LSF cables can be flexible, low-cost alternatives to PVC cables. They are constructed from an altered version of PVC and still generate highly poisonous gas and massive amounts of hydrogen chloride and black smoke gas when they are burned.
  • Smoke from black smoke can block escape routes in the case of fire, and hydrogen chloride gas could be dangerous to people and sensitive equipment.
  • However, LSHF cables are more brittle and cost more due to the absence of PVC, eliminating significant amounts of the toxic gases and smoke, but not more than 0.5 percent HCL when they are burned. Therefore, in a high-risk area with many people and a very narrow escape, LHSF cables are strongly advised.
  • However, in areas with low risk in which evacuation is simple, and a high degree of flexibility is required, PVC could still be an excellent option.
  • The most common misperception can be it is believed that LSF (or LSHF cable can also be a flame retardant. This isn’t necessarily the case. The cables can propagate the fire, even if the emission of fumes is minimal.

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