• 24/ 09, 2019

Ever noticed the warning sign outside an electrical transformer or an enclosure with large wires and cables sprawled all over? The numerous thunderbolt depictions are enough to drive home the point: stay away from high voltage! It is vital to know everything about voltage power and why it is not something you ignore, even when safety is at your disposal.

What is the definition of High Voltage?

High voltage refers to the amount of voltage power that is above the regular norm or threshold. There are two points related to high voltage that describes its essence: it causes sparks in the air and the fact that it can give out electric shocks when one goes close to it. The voltage could be concerning two conductors of a system or a conductor and the ground. For instance, when it comes to electric power transmission, any voltage above 35,000 volts is considered high voltage. The apparatus’ design and insulation are essential to include for its classification.

Any voltage power above 50 volts is considered dangerous for living beings, emphasising on the need to include more safety and ensuring that the circuits, too, adhere to safety standards. Any voltage power above 1000 volts is a high voltage as well. Bearing this in mind, extra-high voltage or EHV are voltages that lie in the range of 345,000 – 765,000 volts.

What are high voltage power cables?

Now that the real and physical power of high voltage is understood, it is easy to bear in mind its workings and structure. Individual conductors carry high voltage and require a specific high voltage power cable for electric power transmission. A typical high voltage power cable requires the following:

  • A conductor
  • Insulation that can be used for underground and under the water
  • Cable and joints to ensure that the high voltage impact is controlled and doesn’t lead to its insulation breaking down

Different types of high voltage cables cater to various applications. Some are crucial for instruments, alternating current (AC) and direct current (DC) power transmission, and systems for ignition. The idea behind having a high voltage power cable system is to prevent any contact between other objects or living beings with a high voltage conductor. Moreover, its leakage current must be aptly controlled and monitored.

The insulation of a high voltage power cable must be regulated even when there’s a spike in high voltage owing to ozone-produced electric discharges in the air. Each cable terminal and joint must have a layer of a metallic shield on the insulation, connected with the ground. This metallic shield is used to equalise the di-electric stress layer that contains the insulation.

Features of a high voltage power cable:

High voltage power cables are special in nature, working with specific switching and distribution panels.

They enable control rooms to switch and be controlled remotely or manually for the testing of individual supply systems.

Sub-stations for high voltage power cable can lower the voltage in a bid to distribute it to local areas.

The semiconducting layers must be seamless and should be a few micrometres. Any fission or space between the fusion of the layers and insulation can be very dangerous.


A high voltage power cable’s structure contains at least one to more conductors, apt insulation and a jacket for protection. Depending on the level of voltage power, the cables can have additional layers for the insulation jacket to control the electric field in the conductor.

More often than not, high voltage power cables are used in the operation of conductors that go beyond 2,000 volts. Bearing this amount in mind, there will be a conductive shield around each insulator conductor which helps in equalising electrical stress. This shield is sometimes called the Hochstadter shield as Martin Hochstadter had patented this technique back in 1916.

Installed at the ends of shields are ‘stress relief cones’.

Power distribution cables of 100,000 V are insulated well with oil and paper. They function via a stiff steel pipe and a semi-stiff or rigid aluminium or lead covering.

Maintenance of high voltage power cables:]

It is crucial to ensure that the high voltage power cable you install for the underground transmission electric power should be of the highest of quality.

While purchasing the right high voltage power cable, ensure that it is durable enough to withstand extreme conditions. Considering such cables deal with high voltage and can cause serious electric shocks, the materials should be made of superior quality and must include a number of energy-efficient technology.

Maintain a checklist of all your cables, especially if it is an industrial setting. A repository of all your wires and cables should help in giving you a clear idea of when the next repair or maintenance check is. Irrespective of its nature, ensure that the cable you use, especially for residential purposes, is a common type so that it becomes easier to understand and maintain it. Let an expert in the field handle the repairs or any check of the high voltage power cables. Despite having a handy manual, it should be looked into with guidance to avoid a catastrophic event. An expert will be able to gauge through the damage and accordingly repair it without any serious repercussions.

For underground cable maintenance, inspect how clean the surroundings are. Clean up the debris or dust around regularly and periodically check its cable joints, splices and other ground connections.

Run the necessary tests to keep up with the maintenance of high voltage power cables. Cable testing and Cable Diagnosis are required to judge the cable’s current condition and locate any breakage.

High voltage power is not something one must take lightly. Often used for commercial, residential and industrial set-ups, high voltage power cables must be routinely checked so that you can save any expenses or avoid unnecessary outages from happening, especially considering how some outages can disrupt work systems and everyday activities. Known for its superior quality with the right ISI marks and approvals, head out to Finolex Cables for premium products and forget all your electrical worries.

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