Substantial technical differences exist between the use of classic PVC coverings and PPE electric cables for construction work involving the handling of electrical materials.
The latter are fire resistant and ideal to be used for a global improvement of the safety systems integrated into the electric circuits. An expert installer must take into particular consideration the relationship of contiguity that exists between the two elements, in order to guarantee to the final user the maximum level of safety in case of voltage drop, short circuit and other problems.
When to use PVC cables
PVC is considered one of the most versatile among the thermoplastic materials. Used as a base material to cover the surface of electric cables, it is particularly suitable for the construction of electrical energy systems made up of rigid cables, long lasting and resistant to any type of temperature. The cables with PVC covering are therefore ideal for outdoor use and are specially designed to give the installer the opportunity to realize both the installation and the raceways.
Cables with PVC covers or insulation are:
- flame retardants
- resistant to various chemicals, including oils, acids and alkalis.
Given their lightness, PVC covers must be used with full knowledge and located in areas not subject to excessive impact or pressure. Furthermore, since the PVC coverings do not guarantee a great resistance to heat, it is advisable not to use them in areas exposed to high temperatures.
When to use PPE cables
One of the main problems that may arise while using electric wires is the short circuit, responsible for fires and propagation of free flames very dangerous for the general safety.
Given the composition of the protections, the cables in PPE or PE are particularly resistant to fire and indicated to ensure therefore higher levels of protection against possible propagation of flames and fire in the event of a short circuit.
In order to be able to use PPE cables in the most congenial way, it is necessary to keep in mind the European legislation, in order to create an adequate compromise on the use of practical, functional and at the same time safe power cables.
For this reason, the main European legislation systems have immediately issued laws designed to guarantee users and installers the maximum degree of safety in the construction of power plants.
The objective of the regulations is to verify, through practical tests, that:
- during the arrangement the cables can not harm the installer;
- the cables resist heat and do not feed any flames;
- in the event of a short circuit, do not cause flames;
- possible splashes of water do not trigger a short circuit;
- the quality of the cable guarantees an optimal yield.
The IEC 60331-11 standard
There are some main protocols, issued specifically to verify the resistance of electric cables at particularly high temperatures. One of these is the international IEC 60331-11 protocol, which provides for the exposure of cables (of standard length) to a flame having a temperature of up to 750 degrees Celsius, for at least an hour and a half.
Other tests are carried out in a similar manner and are dedicated to safeguarding the safety of the installer and the end user, who is primarily responsible for the use of the power plant.
The news of the halogen free market
Thanks to new technological discoveries, the international market for building materials and electricity has undergone a profound innovation, dictated by the urgency of installers to guarantee maximum safety for themselves and others. On this trend, in recent years, there has been a big news on the market, products called halogen free.
The composition of the sheath with halogen-free materials makes these cables valid alternatives for those who want to install power cables with particular characteristics that mainly concern:
- fire resistance;
- non-feeding of open flames;
- a share of emission of toxic gases and almost no fumes.
Halogen-free cables are named with the acronyms LSOH, LS0H or LSZH (also LSFH or OHLS in technical documents in English).