Fire safety is a key consideration in cable applications, particularly in buildings, infrastructure and transport systems. Cables must meet strict performance requirements designed to limit fire development, reduce the spread of flames and support safe evacuation.

PVC has been used in cable systems for decades because its properties can be tailored to combine electrical insulation, mechanical performance and fire safety. Modern PVC cable compounds are specifically formulated for their intended application and can achieve demanding levels of reaction-to-fire performance under European standards.

Fire and Smoke Behaviour

PVC contains chlorine within its polymer structure, which contributes to its fire behaviour and makes PVC inherently difficult to ignite compared with many other common polymers. When appropriately formulated and incorporated into cable systems, PVC can provide good resistance to ignition and flame propagation.

In fire conditions, PVC cable compounds can offer:

  • good resistance to ignition
  • limited flame spread
  • low or controlled heat release
  • absence of flaming droplets with suitable formulations

These characteristics are important because the development and spread of a fire depend not only on whether a material burns, but also on how much heat it releases and how quickly flames can propagate to surrounding materials.

Smoke performance is another important consideration. PVC compounds can be formulated to reduce smoke production and improve smoke characteristics depending on the intended application and the requirements that the finished cable must meet.

The fire performance of a cable should therefore always be assessed on the basis of the complete cable construction and relevant test methods rather than the polymer type alone.

Performance Under European Standards

Fire performance of cables in buildings is assessed under the EU Construction Products Regulation (CPR).

The CPR classification system evaluates several aspects of cable behaviour in fire, including flame spread, heat release, smoke production, flaming droplets and acidity of combustion gases.

Modern PVC cable systems can achieve demanding CPR classifications, including:

  • B2ca reaction-to-fire classification
  • s1 for low smoke production
  • d0 for no flaming droplets or particles

The exact classification depends on the cable design and formulation. The ability of PVC cables to achieve high CPR classes demonstrates that the use of halogens does not in itself determine the overall fire safety performance of a cable.

Fire safety is instead the result of several interacting parameters, including ignition, flame spread, heat release, smoke, toxicity and the conditions in which the cable is installed.

Continuous Development of Fire Performance

PVC cable technology has evolved considerably over recent decades. Compounders, cable manufacturers and research organisations continue to develop formulations that improve reaction-to-fire performance while maintaining the electrical and mechanical properties required from the cable.

Development work includes optimisation of stabilisers, flame-retardant systems and other additives, as well as improved control of heat release, flame spread and smoke behaviour.

Research has also focused on reducing smoke acidity and understanding how combustion products behave under realistic fire conditions. This is particularly relevant for hydrogen chloride (HCl), which is released when PVC burns and has historically been used as an argument against PVC cables.

Modern fire research increasingly recognises that individual smoke parameters should not be considered in isolation. Fire hazard assessment needs to take account of the complete fire scenario, including the amount and rate of material burning, heat release, smoke generation, gas concentrations and exposure conditions.

The continued development of PVC formulations allows cable manufacturers to respond to evolving European standards and increasingly demanding performance requirements.

Understanding Smoke, Acidity and Toxicity

All organic materials produce potentially hazardous smoke when they burn. The composition and hazard of that smoke depend on the material, the amount burning, ventilation conditions, temperature and the stage of the fire.

PVC combustion can release hydrogen chloride, which is acidic and readily detected because of its strong irritant effect. However, acidity alone is not a complete measure of smoke toxicity or overall fire risk.

Hydrogen chloride is highly soluble in water and can interact with moisture and surfaces within buildings, reducing the amount remaining airborne. Research comparing PVC with alternative cable materials has therefore highlighted the importance of assessing smoke toxicity under realistic fire conditions rather than relying on a single indicator such as acidity.

At the same time, parameters such as flame spread and heat release are critical because they influence how quickly a fire develops and how much material becomes involved.

A balanced fire safety assessment considers all of these factors together.

Fire Safety Depends on the Complete Cable System

No single material property determines whether a cable is safe in a fire.

The overall performance of a cable installation depends on factors including the cable construction, the compound formulation, the quantity of cables installed, their location, ventilation and the fire protection measures used in the building.

PVC cable systems can combine strong fire performance with the other characteristics required for reliable electrical installations, including:

  • electrical insulation
  • mechanical durability
  • flexibility where required
  • resistance to environmental conditions
  • long service life
  • cost efficiency

This combination of properties is one reason PVC remains widely used for cable insulation and sheathing in buildings and infrastructure throughout Europe.

Questions & Answers on Fire Performance

1Are halogen-free cables safer than PVC cables?

Cable safety cannot be determined by a single material characteristic such as the presence or absence of halogens. Fire safety depends on the overall performance of the cable system, including its classification under European standards such as the Construction Products Regulation (CPR).

PVC cables offer a balanced fire performance profile, including resistance to ignition, limited flame spread and no flaming droplets. Test results under CPR conditions show that PVC cable systems can achieve fire performance comparable to, and in some cases exceeding, alternative materials, including in terms of heat release rate — a key parameter in fire development.

It is also important to note that smoke acidity is not a reliable indicator of fire safety. In real fire scenarios, carbon monoxide (CO) is the primary toxic threat, while hydrogen chloride (HCl) remains localised and plays a secondary role.

Halogen-free cables are used in certain applications where specific smoke or acidity characteristics are prioritised. The choice of cable material depends on the requirements of the installation and the overall performance of the cable system.

In some applications, such as electric vehicle charging cables covered by EN 50620, halogen-free materials are specified by standard. This means that PVC is not included in these specific cases, even though it is widely used in other cable applications with well-documented safety and performance.

In some applications, such as electric vehicle charging cables covered by EN 50620, halogen-free materials are specified by standard. As a result, PVC is not included in these specific cases, despite its well-established performance in other cable applications.

In other regions, such as the United States, standards like UL 62 allow the use of PVC in charging cables, reflecting different technical approaches to meeting safety and performance requirements. Similar approaches can also be found in other markets, including South Korea, where PVC remains part of the cable system landscape.

2Does PVC produce dangerous smoke in a fire?

All cable materials produce smoke when exposed to fire. The key factors for safety are smoke density, toxicity and fire development.

Well-formulated PVC cable compounds incorporating flame retardants and smoke suppressants achieve strong classifications for smoke production under European standards. Modern PVC cables can meet stringent CPR requirements for smoke behaviour.

In fire scenarios, carbon monoxide (CO) is the primary toxic threat, while other combustion products play a secondary role.

3Is smoke acidity a good indicator of fire safety?

Smoke acidity is often cited in discussions about cable materials, but it is not a reliable indicator of overall fire safety. Fire safety studies show that acidity does not represent smoke toxicity and is not a good measure of real fire hazard. The most critical factor in fire development is the heat release rate, which determines how quickly a fire grows.

While combustion of PVC can produce hydrogen chloride (HCl), this compound is rapidly diluted and remains localised near the fire source. It may contribute to irritation and provide an early warning signal, but it is not the determining factor in fire safety outcomes. Corrosive effects on equipment may be relevant for post-fire damage assessment, but they are not a primary factor in life safety during fire events.

PVC cable systems perform well in terms of heat release and flame spread, which are the key parameters for limiting fire development.

4Do PVC cables meet European fire safety standards?

Yes. PVC cables used in building applications are tested under harmonised European standards and classified under the Construction Products Regulation (CPR).

PVC cable systems can achieve high fire performance classifications, including B2ca, demonstrating their suitability for demanding building environments.

Ongoing development within the European PVC cable value chain continues to improve fire and smoke behaviour in line with evolving regulatory requirements.

References

The following studies and industry research support the fire performance and safety characteristics of PVC cable systems: