Circular No. 07/2001/TT-BCN guiding the implementation of certain technical contents stipulated in Decree No. 54/1999/NĐ-CP dated July 8, 1999 of the Government on the Protection of High Voltage Power Grid Safety

 CIRCULAR

Guidelines for implementing certain technical contents stipulated in

Decree No. 54/1999/NĐ-CP dated July 8, 1999 of the Government

on the protection of high-voltage power transmission networks

Pursuant to Decree No. 74/CP dated November 1, 1995 of the Government on the functions, tasks, powers, and organizational structure of the Ministry of Industry;

Pursuant to Decree No. 54/1999/NĐ-CP dated July 8, 1999 of the Government on the protection of high-voltage power transmission networks,

The Ministry of Industry hereby provides guidelines for implementing certain technical contents stipulated in Decree No. 54/1999/NĐ-CP dated July 8, 1999 of the Government on the Protection of High-Voltage Power Transmission Networks (hereinafter referred to as Decree No. 54/CP) as follows:

1. Technical standards and purposes of using insulated cables

a) Insulated cables are specialized conductors used for overhead lines, coated with appropriate insulation layers suitable for the voltage level. The insulation resistance of the coating layer must not be less than the following value:

b) Insulated cables are used to reduce the width of the safety protection corridor for high-voltage power transmission networks, thereby reducing the number of trees that need to be pruned when high-voltage power transmission networks are extended into the central areas of cities, towns, and districts (hereinafter collectively referred to as cities).

c) Insulated cables must be installed phase-by-phase on insulators as with bare conductors.

d) Insulated cables can be used throughout the entire route or combined with bare conductors on some necessary poles.

đ) Insulated cables should be replaced when the insulation of the coating layer shows signs of aging and cannot withstand ground faults caused by tree branches touching the conductors.

2. Competent units managing high-voltage power transmission networks

a) The competent units managing high-voltage power transmission networks as stipulated in Clause 8, Article 2 of Decree No. 54/CP are economic organizations meeting the conditions for electricity operations as prescribed by law, including:

- For the national power system, the competent units managing high-voltage power transmission networks are the Electricity Transmission Companies, Electricity Companies, and Provincial Electricity Enterprises assigned by Vietnam Electricity Corporation to manage and operate the power transmission network within their respective provinces and cities.

- Other economic organizations meeting the conditions for electricity operations as prescribed by law are competent units managing high-voltage power transmission networks within their own power transmission networks.

b) Organizations owning high-voltage power transmission line and substation facilities but lacking an electricity operation permit may enter into a management contract with other organizations holding such permits to manage and operate the facilities and address issues related to the implementation of Decree No. 54/CP.

Organizations holding an electricity operation permit and entering into a management contract are considered competent units managing high-voltage power transmission networks within the scope of the delegated management.

c) Competent units managing high-voltage power transmission networks must publicly announce their addresses and telephone numbers on mass media for the units authorized to handle issues related to the implementation of Decree No. 54/CP.

3. Safety protection corridors for overhead high-voltage power transmission networks

The length of the safety protection corridor for overhead high-voltage power transmission networks is measured from the point where the conductor is attached to the outgoing pole of the substation to the point where it is attached to the anchor pole before entering the next substation (see Figure 1 - Appendix). The initial and final sections of the line connecting from the pole to the busbar frame of the substation are considered part of the substation facility. Safety standards for these sections are implemented according to the provisions of Article 15 of Decree No. 54/CP.

4. Plants within the safety protection corridor for high-voltage power transmission networks

a) Rice and field crops must be planted at least 0.5 meters away from the edge of the pole foundation and anchor foundation (see Figure 2 - Appendix). The distance of 0.5 meters mentioned above is measured from the outer surface of the concrete portion of the foundation to the natural ground level.

b) Other types of plants must ensure that the distance from the highest point of the plant to the conductor is not less than the provisions set out in Point a, Clause 1, Article 7 of Decree No. 54/CP (see Figure 3 - Appendix). Plants that can grow rapidly within a short period must be cut down to the root and prohibited from being replanted if they regrow within a cycle of inspection and clearance of the corridor and have the potential to cause power grid accidents. Other plants that require pruning will no longer be economically viable, such as coconut, rubber, etc., and must also be cut down to the root and prohibited from being replanted, with immediate compensation provided when constructing high-voltage power transmission lines.

The inspection and clearance cycle of the corridor is once every quarter. Competent units managing high-voltage power transmission networks are responsible for supplementing the list of plant types that can grow rapidly within a short period in their localities to develop plans for clearing the corridor, ensuring safe operation of the power grid.

5. Cutting and trimming trees outside the safety protection corridor for high-voltage power transmission networks

a) Trees outside the safety protection corridor for high-voltage power transmission networks must be cut and trimmed according to the provisions of Clause 2, Article 7 of Decree No. 54/CP (see Figures 4 and 5 - Appendix). Specifically, for tall trees in cities that could fall and hit power lines, competent units managing high-voltage power transmission networks only organize cutting and trimming branches to ensure compliance with the distance requirements set out in Point b, Clause 1, Article 7 of Decree No. 54/CP.

b) For trees of historical, cultural, or special value, before cutting and trimming, competent units managing high-voltage power transmission networks must reach an agreement with the direct management agency of the tree. In cases where an agreement cannot be reached with the aforementioned agencies, the competent unit managing high-voltage power transmission networks shall prepare a document sent to the local Industry Department and the superior agency of the tree management agency to coordinate in finding solutions.

c) For high-voltage power transmission lines under construction, the project owner of the power transmission network is permitted to clear the corridor and cut and trim some trees not covered by Article 7 of Decree No. 54/CP to prevent damage to conductors during construction, ensuring safe construction conditions but must notify the owners of the trees and compensate them according to state regulations.

6. Materials for building walls and roofs of houses and structures within the safety protection corridor for high-voltage power transmission networks

a) The enclosing walls and roofs of residential buildings and structures within the safety protection zone of high-voltage power transmission lines must be constructed from non-combustible materials. Non-combustible materials are those that do not ignite, smoulder, or carbonize under the influence of fire or high temperatures (for example: bricks, tiles, cement asbestos, concrete, metal roofing sheets, glass, etc.).

b) The roof trusses supporting the roofs of residential buildings and structures, windows, and doors do not necessarily have to be made of non-combustible materials.

7. Grounding the metal roofs of residential buildings and structures within the safety protection zone of high-voltage power transmission lines.

Metal roofs of residential buildings and structures within the safety protection zone of high-voltage power transmission lines must be grounded to prevent electrical induction and static electricity phenomena. The grounding process is carried out as follows: A grounding stake made of angle steel L63x63x6, measuring 2 meters in length and buried 1.8 meters deep underground. The metal roof of the building is connected to the grounding stake with a conductor having a cross-sectional area no less than: F6 for round steel; F4 for copper wire; or 40x4 for flat steel. The grounding conductor is connected to the roof using bolt fastening methods and to the grounding stake using welding methods. The value of the grounding resistance is not specified.

The project investor of high-voltage power transmission lines is responsible for completing the grounding of the roofs of these residential buildings and structures before energizing the lines. The owners of the residential buildings and structures are responsible for managing this grounding system.

8. Measures to enhance electrical and construction safety for spans crossing residential buildings and structures.

Overhead high-voltage power lines crossing residential buildings and structures must be enhanced in terms of electrical and construction safety. These measures are specified as follows:

a) The cross-sectional area of the conductors shall not be less than the values specified in the table below:

b) The safety factor of the conductors shall not be less than 2.5 and is calculated according to the following formula:

 Where:

- K_AT = Safety Factor

- _^σKĐ = Breaking strength of the conductor (Electrical Equipment Standards - Table II.5.2)

- _^σCD = Tension calculation value for the conductor

c) Conductors and lightning protection cables of overhead high-voltage power lines crossing residential buildings and structures, if their cross-sectional area is less than 240 mm², shall not be allowed to have joints. Conductors and lightning protection cables with a cross-sectional area of 240 mm² or more may have no more than one joint per phase.²shall not have any joints. Conductors and lightning protection conductors with a cross-sectional area of 240 mm and above may have no more than one joint per phase.²từ cấp trung thế trở lên được phép có không quá một mối nối cho một pha.

d) Insulators in spans crossing residential buildings and structures:

- Conductors and lightning protection cables mounted on suspension insulators (chain insulators) must use fixed clamps. When the power line operates under normal conditions, the safety factor of the chain insulator and its accessories shall not be less than 2.7.

- Conductors and lightning protection cables mounted on post insulators (pin-type insulators) must be double-mounted on two insulators. The safety factor of the insulator, pin insulator, and mounting accessories when operating under normal conditions shall not be less than 3.0.

đ) Poles supporting power lines crossing residential buildings and structures must be steel poles or reinforced concrete poles. The safety factor of the pole, beam, and pole foundation shall not be less than 1.5.

e) For individuals or organizations to be able to renovate or construct residential buildings and structures up to 8 meters above natural ground level, the distance from the lowest point of the conductor under no-wind conditions to the natural ground surface in densely populated areas shall not be less than the following:

Densely populated areas include cities, industrial enterprises, agricultural enterprises, railway stations, bus terminals, concentrated residential areas, or areas expected to develop within the next five years according to the planning approved by the People's Committee of the province or centrally-administered city.

g) High-voltage power lines crossing residential buildings and structures shall not be operated beyond the prescribed load limit. Protective devices and circuit breakers must be tested and meet standards before being put into operation. The management unit's leader has the authority to organize reviews and, if necessary, immediately revise and supplement the dispatching procedures, operational procedures, and fault handling procedures.

9. Compensation for relocation of residential buildings and structures outside the safety protection zone of high-voltage power transmission lines.

Compensation for relocation of residential buildings and structures outside the safety protection zone of high-voltage power transmission lines shall only apply to legally constructed buildings and structures existing prior to the construction of the high-voltage power line and whose relocation is justified.

a) Legally constructed means construction not on encroached land and the owner of the residential building or structure has complete documentation proving the right to use the property or construction permit in accordance with laws on land and construction.

b) Justified reasons include:

- The project investor of the high-voltage power transmission line cannot ensure the safety conditions for residential buildings and structures as stipulated in Clause 2, Article 8 of Decree 54/CP.

- Residential buildings and structures must be partially demolished to ensure the safe distance as stipulated in Point c, Clause 1, Article 8 of Decree 54/CP, but the remaining area is unusable or insufficient for normal living activities according to local regulations, and the owner requests relocation.

- Warehouses and structures with a high risk of fire or explosion such as oil depots, ammunition warehouses, gas cylinder filling areas, production areas emitting corrosive gases like chlorine (Cl₂), sulfur dioxide (SO₂), hydrogen sulfide (H₂S).₂), sulfur (SO₂), hydrogen sulfide (H₂S).

- Economic, cultural, security, defense, communication facilities, and places where people frequently gather (theaters, bus terminals, schools, etc.). In cases where the competent authority agrees to allow high-voltage power lines to cross these structures, the lines must be strengthened in terms of electrical and construction safety as prescribed.

- All residential buildings and structures where people regularly live or work within the safety protection zone of 500 kV high-voltage power transmission lines, except specialized structures serving the power lines.

c) Livestock sheds, toilets, water tanks, wells, paths, drying yards are not eligible for compensation for relocation outside the safety protection zone of high-voltage power transmission lines, but if the main structure must be relocated, the project investor of the high-voltage power transmission line must provide compensation for relocating these auxiliary structures.

10. Agreement on the expansion or new construction of residential buildings and structures within the safety protection zone of high-voltage power transmission lines.

a) Competent authorities shall only issue construction permits for houses and works within the safety protection zone of high-voltage power transmission lines after reaching a written agreement with the authorized power grid management unit.

b) The project owner shall submit a written request along with certified copies of relevant documents concerning the house, land, and construction permit to the authorized power grid management unit.

c) The terms of the agreement between the authorized power grid management unit and the project owner will vary depending on specific circumstances but shall include issues such as determining safe distances according to Decree No. 54/CP, agreements regarding time, responsibilities, and costs for tasks like power disconnection, raising wires, enhancing electrical and construction safety of the line, and monitoring electrical safety during construction.

d) Within fifteen days from the date of receipt of the request and related documents, the authorized power grid management unit must respond in writing to the project owner. In cases where an agreement cannot be reached, the authorized power grid management unit must clearly state the reasons in its written response.

đ) If the project owner finds the reasons for the refusal of agreement by the authorized power grid management unit unsatisfactory, they may submit the matter to the local Industry Department for intervention and resolution.

11. Distance from high-voltage conductor to road surface at crossing points

The vertical distance from the high-voltage overhead line conductor when in static condition to the road surface of automobiles and railway tracks shall have the following specified values:

12. Distance from high-voltage conductor to water surface of inland waterway at crossing points

a) Inland waterways are defined in Article 1 of Decree No. 171/1999/NĐ-CP issued by the Government on December 7, 1999, detailing the implementation of the Ordinance on Protection of Transport Infrastructure for River Transport Works.

At crossing points between overhead high-voltage lines and inland waterways, the vertical distance from the lowest point of the conductor to the highest average annual water level when in static condition shall be equal to the clear height according to the technical grade of the inland waterway plus the discharge clearance distance, with the following specified values:

b) For maritime traffic, specific regulations apply for each case. Where ships or other water transport means with large dimensions (as stipulated in Article 22 of the Ordinance on Protection of Transport Infrastructure) operate on inland waterways crossed by high-voltage lines, in addition to the required operational license, the vessel owner must also contact the authorized power grid management unit to implement necessary safety measures.

13. Safety protection zone for underground cable routes

a) The safety protection zone for underground cable routes is defined in Article 12 of Decree No. 54/CP (see Figure 9 - Appendix). The installation of underground cables and markers is carried out according to Chapter II.3 of Electrical Equipment Regulations No. 11TCN-19-84.

b) It is not permitted to construct houses or works within the safety protection zone for underground cable routes or carry out activities that could damage the cables.

c) When it is necessary to carry out activities that may affect the normal operation of underground cable routes, the entity conducting these activities must take safety measures and obtain the agreement of the authorized power grid management unit.

14. Safety protection zone for substations

The width of the safety protection zone for substations as stipulated in Points a and b of Clause 1, Article 14 of Decree No. 54/CP applies only to suspended substations and open substations, which are types of substations with transformers placed outdoors (see Figure 10 - Appendix).

This regulation does not apply to enclosed substations, which are types of substations with transformers located in dedicated rooms inside or adjacent to factory buildings, offices, or hotels.

15. Painting colors and placing signal lights on poles

a) The investor of high-voltage power transmission projects must paint white-red warning colors and place signal lights on poles with heights of 80 meters or more. The white-red warning color starts being painted from a height of 50 meters or more. Below 50 meters, anti-corrosion paint or the original galvanized layer may be applied. Signal lights should be placed at the top of the pole or on the highest conductor.

b) Some poles with heights ranging from 50 meters to 80 meters but located in positions with superior elevation compared to the surrounding terrain may be painted and fitted with signal lights upon the recommendation of the Ministry of National Defense or the Civil Aviation Administration of Vietnam.

16. Placing signs and markings when high-voltage overhead lines cross inland waterways

a) According to Articles 10 and 11 of Decree No. 171/1999/NĐ-CP issued by the Government on December 7, 1999, detailing the implementation of the Ordinance on Protection of Transport Infrastructure for River Transport Works: "The inland waterway system is divided into three grades: Central Inland Waterway System; Special-Purpose Inland Waterway Routes; Local Inland Waterway Systems. The Central Inland Waterway System and Special-Purpose Inland Waterway Routes are decided and announced by the Minister of Transport. Local Inland Waterway Systems are decided and announced by the Chairman of the Provincial People's Committee."

Based on the above content, channels and creeks with boat traffic but not designated as part of the inland waterway system do not need to have signs and markings placed on both banks.

b) When high-voltage lines cross inland waterways, the investor of the high-voltage power transmission project must place signs and markings on both banks according to the model prescribed by the Ministry of Transport.

17. Responsibilities of the investor of high-voltage power transmission line projects and of the authorized power transmission line management units

a) For the investor of high-voltage power transmission line projects

- Before energizing and accepting the high-voltage power transmission line project, the investor must complete the relocation or renovation of houses, structures, trimming of trees, etc., in accordance with Decree No. 54/CP. Any existing issues or newly arising problems that cannot be resolved must be documented separately with the agreement of the authorized power transmission line management unit regarding the content, measures, and time for rectification.

- The investor of the high-voltage power transmission line project must hand over all relevant files concerning compensation, relocation, and renovation of houses and structures within the safety protection zone of the high-voltage power transmission line to the authorized power transmission line management unit. These files must be confirmed by the Compensation Council and the persons entitled to compensation.

b) For the authorized power transmission line management units:

- Issues remaining in the safety protection zone of the high-voltage power transmission line due to the transition from implementing Decree No. 70/HDBT to implementing Decree No. 54/CP, if the responsibility lies with the investor of the high-voltage power transmission line project, the authorized power transmission line management unit must compile statistics, develop plans for renovation and rectification, and organize implementation.

- If the responsibility lies with other organizations or individuals, these issues must be compiled separately and reported to the People's Committee of the province or centrally-administered city for handling according to their authority.

This Circular shall take effect fifteen days from the date of signature. During the implementation process, if there are any difficulties or new issues that need to be addressed, please submit written documentation to the Ministry of Industry for review and resolution.