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What Is Insulating Material in Cable?

Posted : 14-February-2022

Insulating cable materials are required in underground cables. As a result, selecting the appropriate insulating cable is important. Before purchasing, you show know a few things about insulating cables here are some qualities of the insulating cable materials should be as follows:

  • To avoid power losses, a good insulating cable is required.
  • To reduce the electrical breakdown of the cable, it must have a high electrical conductivity.
  • To survive the mechanical processing of underground wires, they must have a good tensile property.
  • It should be non-hygroscopic, which means it shouldn’t take moisture from the air or the soil. It reduces the insulating resistance of the cable and speeds up its breakdown.

Different types of insulating materials that are utilized in underground cables:

The kind of insulating material for use is determined that insulating cable material is determined by the purpose for which it is intended and desired level of insulation. Rubber, VIR, paper, Polyvinyl Chloride (PVC), Varnished Cambric, Polyethylene, Gutta-Percha, Silk, Cotton, enamel, and other insulating cable materials are used for the manufacture of cables.


Rubber can be made from the creamy fluid of tropical trees or from oil-based materials. It possesses a conductivity of 2 to 3, a dielectric strength of 30 kV/mm, as well as an insulation resistivity of 1017 cm. As a result, pure rubber could be utilized in underground cables as an insulating material.

  • Vulcanized India Rubber (V.I.R.)

It is a type of rubber that has been vulcanized and made by combining pure rubber with mineral stuff like zine oxide, red lead, and 3 to 5 percent Sulphur. The resulting product is rolled onto thin sheets before being sliced into strips. Pure rubber lacks the mechanical strength, durability, and wear resistance of vulcanized India rubber. As a result, low and moderate-voltage wires are typically insulated with VIR.

  • Impregnated paper:

Rubber insulation has practically been replaced by this sort of insulation. Because of its inexpensive cost, low capacitance, and good insulating resistance, it is widely used. The only disadvantage is that paper is hygroscopic; as a result, paper-insulated underground wires are constantly covered and never left open.

VIR cables, on the other hand, are less expensive and more robust than paper-insulatedcables for smaller installations with short lengths and several joints.

  • Varnished cambric:

This form of insulation is known as varnished cambric. Because varnished cambric is hygroscopic, metallic sheaths are always used to protect underground cables.

  • Polyvinyl chloride (PVC):

PVC is a man-made insulating cable. It’s made from acetylene polymerization and comes in the form of a white powder. Over a wide temperature range, polyvinyl chloride provides great insulating resistance, good dielectric strength, and mechanical durability.

As a result, in harsh environments like a cement plant or a chemical plant, this form of insulation is chosen over VIR.

The properties of the insulation are used to determine how long a cable will last and how well it will function. As a result, selecting the right insulating cable material for the wires is critical.

What’s the difference?

The difference between Thermoplastic and Thermoset is that they are two types of insulating polymers often used to coat copper wire.


When exposed to a sufficiently high temperature, this substance softens and even melts. To put it another way, when the material is first compounded, it becomes relatively rigid but flexible, similar to most polymers we come across in our daily lives. It softens and melts if it is subjected to high temperatures. The main rationale for using thermoplastic insulation is that it is the most cost-effective option.

The following are some of the most regularly used thermoplastic insulations today:

  • PVC (Polyvinyl Chloride)
  • PE (Polyethylene)
  • PVDF
  • Nylon


When exposed to high temperatures, this substance, on the other hand, does not degrade. It becomes “rubbery” after being combined and fixed, and retains its qualities even when exposed to high temperatures. Where the wire or cable will be subjected to high temperatures, thermoset insulations are typically employed.

The following are some of the most often-used thermoset insulations:

  • XLPE
  • CPE
  • EPR

Effect of Moisture on Insulation

When an insulating cable material is exposed to moisture in a humid environment, it absorbs some of it. Water vapors are absorbed on the surface first, then diffuse, reducing the moisture concentration gradient, and eventually not absorbed into the lower vapor concentration zone.

When the electronic components are turned off, moisture diffusion occurs in the insulating cable material. Moisture dissolves from the insulating cable material when the current is conveyed by the electrical devices.


Check if other materials have been used in combination with FEP for insulation when purchasing Category cables plenum. The material that covers your ethernet cables is called insulation and is made of copper.