Discover the science behind PVC cable safety
Studies and tests show that, due to its intrinsically self-extinguishing characteristics, PVC is difficult to ignite and does not sustain combustion.
The presence of chlorine in the polymer structure makes PVC ignitability rather difficult, even in absence of any flame retardant. This explains why, contrary to many other materials, there is no sustained lateral flame spread.
Furthermore, thanks to the charring properties of PVC, there are no flaming droplets with PVC products. Under standardised test conditions, in which the sample is forced to burn, PVC typically generates a dense smoke. However, in a real fire situation, when PVC products do not completely burn or represent a small part of burnt materials, the smoke contribution from PVC is generally not so relevant.
Unlike odourless toxic gases, such as carbon monoxide that is by far the most hazardous element in a fire, the presence of hydrogen chloride generated by PVC combustion can be detected at totally harmless trace levels, due to its distinctive smell. As such, the emission of HCl (hydrogen chloride) gas at an early stage of fire acts as a ‘warning’ signal to people to evacuate the area immediately.
Continued innovation to make PVC cables even more fire safe
New formulations for PVC cables are currently under development to further improve their performance in fires. Nanotechnologies, too, represent an interesting perspective for the development and use of efficient functional additives in polymers.
The results of an experimental work carried out by the University of Piemonte Orientale, Italy, show that positive effects at nanoscale level are evident even with a limited amount of additives in several features, combining chemical effects on thermal stability, degradation and HCl evolution with improved or unmodified physical performances.
PVC4Cables is funding strong R&D in low smoke acidity compounds, and actively disseminating data through scientific journals, conferences, and webinars.
PVC advantages in case of fire
To be considered safe, electric cables installed in any type of construction or engineering work, need to comply with essential safety requirements. All cables must be placed on the European market as CE marked with an available Declaration of Performance. Safety requirements are listed in two EU regulatory documents:
The Low Voltage Directive
The Construction Products Regulation
The Construction Products Regulation (Regulation (EU) No 305/2011, CPR) sets the harmonised technical conditions for free circulation of products within the European Union and identifies a number of essential requirements to respect, including reaction-to-fire performance of products in the event of an outbreak of fire.
Following the publication of the products standards and of all the necessary supporting standards related to test methods and classification, the CPR basic requirements related to safety in case of fire for construction works came fully into force for cables on 1 July 2017.