Regulations on buffer zones of overhead high-voltage transmission lines in Vietnam

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1. Buffer zones of overhead high-voltage transmission lines in Vietnam

According to Article 11 of Vietnam's Decree 14/2014/ND-CP stipulating the buffer zones of overhead high-voltage transmission lines (amended by Points a, b and c Clause 7 Article 1 of the Decree 51/2020/ND-CP)

Regulations for transmissions lines with bare conductors, insulated conductors and buffer zones:

- The length of corridor is from the position where the line goes out of the protection boundary of this station to the position where the line goes into the protection boundary of the next station;

- The width of corridor is limited by 02 vertical planes to two side of the line and parallel with the line with the distance from the outmost line to each side when the line is in the static condition as specified in the following table:

- The height of corridor is from the bottom of pole foundation to the heighest point of the works plus the safety distance vertically specified in the following table:

Note: Buffer zones of above-ground or overhead cables shall cover an area of 0.5m from the outermost cables to the outside.

2. Trees inside and outside buffer zones of overhead high-voltage transmission lines

According to Article 12 of Decree 14/2014/ND-CP (amended by Points a, b and c Clause 8, Article 1 of Decree 51/2020/ND-CP) regulations on distance between trees inside and outside buffer zones of overhead high-voltage transmission lines is as follows:

For trees inside buffer zones of transmission lines

- For power lines with voltage up to 35 kV in cities, towns and townships:

+ For conducting line with voltage up to 35 kV in cities, towns…, the distance from any point of the trees to the conducting wire in the state of maximum deflection is not less than the distance specified in the following table:

+ For the line with voltage from 110 kV to 500 kV in cities, towns…, the trees must not be higher than the lowest conducting line except for special cases, there must be technical measures to ensure the safety permitted by the People’s Committees of provinces and centrally-run cities (provincial People’s Committees). The distance from any point of the trees to the conducting line at the state of maximum deflection must not be less than the distance specified in the following table:

+ For the lines outside cities, towns…, the distance from the highest point of the trees vertically to the height of the lowest conducting line at the state of maximum deflection is not less than the distance specified in the following table:

+ For the overhead conducting line across special-use forest, protection forest, production forest and garden, the vertical distance from the average height of trees maximally grown to the lowest conducting line at the state of maximum deflection must not be less than distance specified at Point c, Clause 1 of this Article.

For trees outside buffer zones of transmission lines and outside cities and towns

The distance between any part of a tree when it falls and any part of a transmission line shall be longer than the distance specified in the following table:

Note:

- For trees which rapidly grow within 03 months and possibly violate the distance specified in Clause 1 and 2 of this Article. For the trees which have no longer economic efficiency must be fallen and not be planted again.

- Rice, crops and plants must only be planted at least 0.5 m from the pole foundation and sleeper.

3. Requirements for houses and workplaces to remain inside buffer zones of overhead high-voltage transmission lines with a voltage of up to 220 kV in Vietnam

According to Article 13 of Decree 14/2014/ND-CP (amended by Points a, b and c Clause 9 Article 1 of Decree 51/2020/ND-CP) stipulating requirements for houses and workplaces to remain inside buffer zones of overhead high-voltage transmission lines with a voltage of up to 220 kV in Vietnam:

- Houses and constructional works are permitted to exist within the safety corridor of overhead conducting line with voltage up to 220 kV if meeting the following conditions:

+ Roof and wall must be made of non-combustible materials.

+ There is no obstruction of checking, maintenance and replacement of parts of the transmission lines.

+ The distance from any part of houses or works to the nearest conducting line when the line is at the state of maximum deflection is not less than the distance specified in the following table:

+ The electric field intensity is less than 5 kV/m at any point outside the house and one meter (01) from the ground and less than or equal to 1 kV/m at any point inside the house and one meter (01) from the ground.

Note: For houses and works within the safety corridor of overhead conducting line with voltage of 220 kV, besides meeting the above conditions (Article 13 of Circular 05/2021/TT-BCT dated September 22, 2021).

+ Minister of Industry and Trade shall elaborate on the scope and techniques for grounding of metal structures of houses and structures inside and adjacent to buffer zones of overhead 220 kV transmission lines and adjacent to buffer zones of 500 kV transmission lines.

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