Consolidated Document No. 15/VBHN-BCT: National Technical Regulation on Electrical Engineering (Testing, Operation and Construction of Power Equipment)
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Based on:15/VBHN-BCT - Government Official Gazette
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This is a consolidated document authenticated by the Ministry of Industry and Trade on March 13, 2026, merging Circular No. 40/2009/TT-BCT (promulgating the National Technical Regulation on Electrical Engineering, effective March 29, 2010) with amendments under Circular No. 51/2025/TT-BCT dated November 11, 2025 (promulgating QCVN 26:2025/BCT on Electrical Engineering - Power Grid System, effective June 1, 2026). It sets out national technical regulations QCVN QTĐ-5, QTĐ-6 and QTĐ-7 covering testing, operation-maintenance, and construction of power grid equipment (transmission and distribution lines, substations up to 500 kV), hydroelectric plants of 30 MW or more, and thermal power plants of 1 MW or more connected to the national grid. The bulk of the content is technical procedure: inspection during installation, completion testing before commissioning, and periodic inspection (generally every 3 years) for generators, transformers, hydraulic turbines, dams and hydraulic structures - including earth-resistance measurement, insulation-resistance measurement, dielectric tests, vibration measurement, and load-rejection tests. Circular 51/2025/TT-BCT repealed all six chapters of Part II (grid equipment, substation and transmission-line testing) in the former Volume 5, replacing them with the new QCVN 26:2025/BCT, effective from June 1, 2026. This is a technical electrical-safety standard aimed at the power industry (power plant owners, transmission and distribution operators), not tax, accounting, e-invoicing, labor, or customs matters. It therefore falls outside RegHub's core coverage for SME owners and accountants, and is retained only as technical background for businesses operating in the power sector.
Overview
Consolidated Document No. 15/VBHN-BCT, authenticated by the Ministry of Industry and Trade on March 13, 2026 (signed by Deputy Minister Truong Thanh Hoai), merges:
- Circular No. 40/2009/TT-BCT dated December 31, 2009 - promulgating the National Technical Regulation on Electrical Engineering, effective March 29, 2010.
- Circular No. 51/2025/TT-BCT dated November 11, 2025 - promulgating QCVN 26:2025/BCT (Electrical Engineering - Power Grid System), amending Circular 40/2009/TT-BCT, effective June 1, 2026.
Scope
The regulation covers inspection of electrical equipment in three groups:
- Power grid equipment: transmission and distribution lines and substations up to 500 kV (excluding inspection of poles and foundations).
- Hydroelectric plants: hydraulic structures of all hydro plants connected to the national grid (except special dams under Decree 143/2003/ND-CP); electrical equipment of hydro plants of 30 MW capacity or more.
- Thermal power plants: mechanical-electrical equipment (boilers, steam/gas turbines, generators) of plants of 1 MW capacity or more.
Main content - Volume 5 (Testing of Power System Equipment)
Volume 5 has four parts: Part I (General provisions), Part II (Substations, transmission lines - now repealed, see Changes below), Part III (Hydroelectric plants), Part IV (Thermal power plants).
Three types of inspection run throughout the regulation:
- Inspection during installation - confirming each construction stage on site.
- Completion inspection - confirming overall quality before commissioning.
- Periodic inspection - generally every 3 years, graded on a 4-tier A/B/C/D scale (from "no non-conformity" to "serious non-conformity requiring immediate repair").
For hydroelectric plants, typical inspection items include: earth-resistance and insulation-resistance measurement, dielectric withstand tests (test-voltage tables keyed to generator capacity), stator-rotor air-gap measurement, dielectric loss angle (Tgd) measurement, no-load saturation and three-phase short-circuit characteristic tests for generators, governor and intake-gate operation tests, inlet-valve tests, vibration measurement on rotating equipment, first-run testing, automatic start/stop testing, load-rejection testing, emergency-stop testing, and rated-load testing. For concrete dams, periodic inspection focuses on settlement, lateral displacement, erosion around the dam abutment, and new cracks.
Changes under Circular No. 51/2025/TT-BCT
Circular 51/2025/TT-BCT (effective June 1, 2026) has:
- Updated the legal basis for issuance, citing Electricity Law No. 61/2024/QH15 and the June 14, 2025 Law amending the Law on Standards and Technical Regulations, in place of the earlier legal citations.
- Repealed all six chapters of Part II (testing of grid equipment, substations, transmission and distribution lines) in Volume 5, per Appendix S of the attached QCVN 26:2025/BCT.
- Assigned the Electricity Authority and the Industrial Safety Techniques and Environment Authority to guide and inspect compliance with the new regulation.
In short, from June 1, 2026, testing of grid equipment (substations, transmission lines) will follow the new QCVN 26:2025/BCT rather than the old Part II of Volume 5; the provisions on hydroelectric and thermal plants (Parts III and IV) remain in force under this consolidated document.
Effective dates
- Original Circular 40/2009/TT-BCT: effective 45 days after Official Gazette publication (in force since March 29, 2010).
- Amendments under Circular 51/2025/TT-BCT: effective June 1, 2026.
Who must comply
Ministries, ministerial-level agencies, provincial People's Committees and related organizations and individuals - primarily power plant owners/operators and transmission-distribution utilities - are responsible for implementation. This is a technical electrical-safety regulation specific to the power sector, with no content relating to tax, invoicing, labor, or customs.