Why thickness of Insulation depends on Voltage not Current?

insulation depends on voltage

Hey, you may hear the thickness of the insulation arrangement of an Electrical system depends on voltage not current but why?
Today we are going to discuss about it. Insulation arrangement is a very important factor in an electrical system. Insulation provides safety, and reduces the chances of short circuits, faults, fire, etc.

There are some important reasons why the thickness of insulation depends upon the voltage which are explained below,

Insulation Breakdown

The main important reason of why insulation depends upon voltage is the breakdown of insulation. Insulation materials are made of dielectric materials. If an insulator has more thickness, then the dielectric strength also be more. The dielectric strength of an insulator depends upon the applied voltage across. If we apply a high voltage above its capacity then the dielectric strength will be weak and the insulator goes into the breakdown. When an insulator goes into the breakdown, it loses its insulation property and it starts to conduct current.

So, now you may understand if the thickness of the insulation is more it can withstand more voltage and can insulate it.

Electrostatic Pressure

When any conductor carries voltage and current, voltage induction occurs in that conductor. As a result, electrostatic pressure occurs across the insulation of that conductor. This electrostatic pressure depends upon the voltage if the carrying voltage is more then the electrostatic pressure will be more.

The electrostatic pressure creates changes in the molecular structure of the insulator and forces it to go to the breakdown. So more thickness of the insulator is required to prevent damage. So when a conductor is used to carry high voltage, its insulation should be more.

Voltage Gradient

When a conductor carries voltage, a voltage gradient is developed along the length of the conductor. Insulation of the conductor absorbs the voltage gradient. If the voltage is more then the voltage gradient will be more, but if the thickness of the insulation is less then it will not able to absorb the voltage gradient. So, the thickness of the insulation is very important when the conductor carries a high voltage.


Mainly, in case if electrical cables, much more insulation is provided compared to its carrying voltage. Suppose a cable is manufactured for 230V, but insulation is provided to that cable above 600V. This is for only safety purposes. When an electrical cable carries high voltage it is very dangerous even it carries very little current.

If a cable carrying a very high ampere current and very low voltage, that is not so much dangerous but if a cable carrying low current and high voltage, it is very dangerous. So any conductor or cable carrying high voltage should have more insulation arrangement.

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Why thickness of Insulation depends on Voltage not Current? Why thickness of Insulation depends on Voltage not Current? Reviewed by Author on February 29, 2020 Rating: 5
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