How to determine the voltage of power lines: simple methods

If you are a fan of country walks and picnics, and hunting and fishing is your passion, it is likely that someday you will come under dangerous stress in the power transmission zone. After all, you should not come close to certain electric highways. For an electrician, determining the voltage is a simple task. How can a lay person find out what voltage in the power line is dangerous to life and health? Below we will tell the readers of the site Elecroexperthow to determine the voltage of power lines by their appearance, the number of insulators and other parameters.

Danger under power lines

OHL classification

The voltage of the power lines can be:

  1. Low voltage, 0.4 kilovolts, transmitting electricity within small towns.
  2. Medium, at 6 or 10 kilovolts, transmitting electricity to a distance of less than 10 km.
  3. High voltage, 35 kilovolts, for power supply of small cities or towns.
  4. High-voltage, 110 kilovolts, distributing electricity between cities.
  5. High-voltage, at 150 (220, 330, 500, 750) kV, transmitting energy over long distances.

The highest voltage on power lines is 1150 kilovolts.

Safe distances

The labor protection rules for each power line voltage determine the minimum distances to the parts that conduct current. Reducing this distance is prohibited.

Table of safe distances to overhead lines

Determination of voltage by appearance

The next stage is the determination of the power lines.

How to know the voltage on the power line by its appearance? The easiest way to do this is by the number of wires and the number of insulators. The easiest way is to determine by insulators.

There are overhead lines of different voltage classes. Let's consider each one in turn.

Power lines of 0.4 kilovolts (400 Volts) are low-voltage, found in all settlements. They always use pin insulators made of porcelain or glass. Supports are made of reinforced concrete or wood. There are two wires in a single-phase line. If there are three phases, there will be four or more conductors.

0.4 kV OHL

Next are the power lines for 6 and 10 kilovolts. Visually, they are indistinguishable from each other. There are always three wires. Each uses two pin porcelain or glass insulators or one, but a larger denomination. These paths are used to power transformers. The minimum distance to the parts conducting current here is 0.6 m.

HVL 10 (6) kV

Often, in order to save, they combine the suspension of conductors of 0.4 and 10 kV. The security zone of such routes is a distance of 10 m.

In the transmission line for a voltage of 35 kV, suspension insulators are used in an amount of 3 to 5 pieces in a garland to each of the three phase wires.

OHL 35 kV

Typically, such airways do not pass through cities. The distance is considered permissible - 0.6 m, and the security zone is determined by 15 meters. The supports should be reinforced concrete or metal, with current carrying conductors spaced apart from each other by an acceptable distance.

In a 110 kV power transmission line, each of the wires is mounted on a separate string of 6-9 suspended insulators. Minimum close to the conductors is a distance of 1 meter, and the security zone is determined by 20 meters.

VL 110 kV

The material for the support is reinforced concrete or metal.

If the voltage is 150 kV, 8-9 suspension insulators are used for each garland in the power transmission line. The distance of 1.5 m from the current conductors is considered to be minimal in this case.

OHL 150 kV

When the voltage is 220 kV, the number of insulators used is in the range of 10 to 40 units. The phase is transmitted over a single wire.

HVL 220 kV

The lines are used to bring electricity to large substations. The smallest distance to the conductors is 2 m. security zone - 25 m.

In subsequent classes of high voltage power lines, a difference appears in the number of wires per phase.

If two conductors are installed on one phase, and insulators in garlands of 14 each, you have a 330 kV trunk.

OHL 330 kV

The minimum distance to live parts in it is considered to be 3.5 m. The necessary increase in the security zone to 30 m. The material for the supports is reinforced concrete or metal.

If the phase is split into 2-3 conductors, and the suspension insulators in garlands of 20 each, then the voltage of the overhead line is 500 kV.

OHL 500 kV

The security zone in this case is limited to 30 meters. A distance of less than 3.5 m to the wires is considered dangerous.

In the case of phase separation into 4 or 5 conductors, the connection of which is circular or square, and the presence of 20 or more insulators in the garlands, the voltage of the overhead line is 750 kV.

OHL 750 kV

The security territory of such routes is 40 m, and approaching the conductive parts closer than 5 m is life threatening.

OHL 1150 kV

This route should not be approached more than 8 meters. You can see such a high-voltage line, for example, on the section of the Siberia-Center highway.

Get detailed information about any overhead line, its location can be on an interactive map on the Internet.

Support marking

It is possible to determine the power of overhead lines by markings applied directly to the supports. The first letters in this entry are capital letters, meaning the voltage class:

  • T - 35 kV,
  • C - 110 kV,
  • D - 220 kV.

Through the dash write the line number. The next figure is the serial number of the support.

Support marking

Rail networks

About 7% of the electricity generated at power plants in Russia is transmitted along the high-voltage lines to railway facilities. In general, the length of the railroad track is 43 thousand kilometers. Of these, 18 thousand km are powered by a direct current of 3,000 volts, and the remaining 25 thousand km are powered by an alternating current of 25,000 volts.

Railway transport

The energy of electrified roads is used not only for the movement of trains. It is fed by industrial enterprises, settlements, other real estate objects located along the railways or in close proximity to highways. According to statistics, more than half of the electric power of the railway contact network is spent on power supply to facilities not included in the transport infrastructure.


After it was possible to find out how the voltage on the power lines can be determined by the number of insulators, it remains to understand how much this method can be trusted.

Climatic conditions in Russia are quite diverse. For example, the temperate continental climate in Moscow differs significantly from the humid subtropics of Sochi. Therefore, overhead lines of the same voltage class, located in different climatic and natural conditions, can differ from each other both in the type of supports and in the number of insulators.

In the case of a comprehensive analysis of all the criteria proposed in the article, the definition of power line voltage by external signs will be quite accurate. But what can be the voltage in a particular high-voltage line, local energy experts will tell you with 100% accuracy.

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