Halogen-free and fireproof cables

Halogen-free and fireproof cables

In addition to reliability, modern electrical and related installations are to provide people in the rooms with maximum safety, also during random events such as fires. The answer to the general demand are cables and halogen-free and fireproof cables which are more and more widely used in construction.

Halogen-free and fireproof cables - a function in installations particularly exposed to fires

Halogen-free cables and wires are made of materials that do not contain chlorine, fluorine, bromine and iodine. Their task is not to conduct electricity during a fire (although they most often ensure delivery to a certain ambient temperature and at a specified time), but to have no side effects such as corrosion, poisonous gases and smoke. In turn, fireproof cables ensure not only the absence of gas emissions, corrosion and smoke, but also sufficiently long and effective control and operation of certain installations, e.g. alarm systems, even during a fire.

Halogen-free cables - the most important features

The insulation of halogens and cables is usually made of polyvinyl chloride (PVC), chloroprene rubber (CR) or chlorinated polyethylene (CM). Although these materials show little or no flammability and are self-extinguishing, they cause corrosion and the formation of toxic vapors (hydrogen chloride, hydrogen fluoride). Due to these properties, the damage caused by corrosion is often greater than that caused by the fire itself.

Cables and halogen-free wires are devoid of four harmful elements. Their insulation is made of polymers based on pure hydrocarbons - polyethylene (PE) or polypropylene (PP). Combustion of both PE and PP does not produce any corrosive and toxic gases, only water vapor and carbon dioxide. Unfortunately, polyethylene and polypropylene are not self-extinguishing materials, on the contrary, they are flammable. Therefore, in order to meet safety requirements, halogen-free cables and wires must be made in a flame-retardant and self-extinguishing version. This effect is achieved through the use of special polymers containing an admixture of agents such as aluminium hydroxide. As a result of heating, crystalline water is separated in the aluminium hydroxide, which on the one hand cools the place of the fire, and on the other hand, through the water vapor, prevents the flow of oxygen and chokes the flames.

Fireproof cables - in which installations are they used?

The reaction of cables and wires in the electrical, as well as control and alarm systems during a facility fire is of great importance from the point of view of the safety of people and property. The most important factors when choosing cables and wires from the point of view of fire are the following:

• reaction of insulation when exposed to flames, in particular flammability and tendency to spread fire,

• Consequential damage caused by formation of corrosive and toxic gases

• smoke emission - adverse effect of smoke in the form of darkening of evacuation routes and preventing or hindering firefighting operations.

Power cables and cables, as well as control and alarm cables, should be non-flammable, do not transmit fire, emit toxic gases and do not generate smoke. Alarm installation and control of multiple devices are key areas both from the point of view of evacuation and protection of property, therefore, in addition to the above conditions, they must also ensure a sufficiently long reliable operation at high temperature and in the presence of fire.

Advantages of high-quality safety cables

Safety wires and cables should exhibit a number of properties during a fire, the most important of which are:

• resistance to flames and flame retardance, therefore no flame transfer,

• no emission of corrosive and poisonous gases,

• low smoke emission,

• safety of the electrical function longer than in the case of a standard installation,

• preservation of insulation durability for a specified time, depending on the ambient temperature.

Of course, these are not all features of halogen-free and fire-resistant cables and wires. In specific operating conditions, which certainly includes a fire, other factors should also be taken into account when selecting the cabling, e.g. resistance to radiation or the backup time of safety systems.