CN Quality Check
Standards Comparison Tool
EXECUTIVE SUMMARY
This report compares GB 50065-2011 (Code for design of grounding of electrical installations) and BS 7430:2011+A1:2015 (Code of practice for protective earthing of electrical installations). Both are TIER 3 design codes with NEQ (Not Equivalent) status due to differing mandatory parameters versus guidance-based values. The key procurement implication: Chinese grounding designs require specific resistance targets (e.g., ≤4Ω for substations) that may not align with BS 7430’s flexible approach, necessitating additional engineering verification.
APPLICABLE CHINESE STANDARDS
| Standard No. | Title (Chinese) | Scope | Mandatory/Recommended | Status |
|---|---|---|---|---|
| GB 50065-2011 | 交流电气装置的接地设计规范 (Code for design of grounding of electrical installations) | Design of grounding systems for AC electrical installations up to 220kV | Mandatory (GB) | Current |
| GB 50057-2010 | 建筑物防雷设计规范 (Code for design protection of structures against lightning) | Lightning protection grounding design | Mandatory (GB) | Current |
| GB 50169-2016 | 电气装置安装工程接地装置施工及验收规范 (Code for construction and acceptance of grounding installations) | Installation and acceptance of grounding systems | Mandatory (GB) | Current |
| 14D504 | 接地装置安装 (Grounding device installation) | National standard design atlas for grounding installation | Recommended (图集) | Current |
STANDARD TIER CLASSIFICATION
| Standard | Tier | Description |
|---|---|---|
| GB 50065-2011 | TIER 3 — Design Code (设计规范) | Defines design methodology, calculation formulas, and mandatory parameters for grounding systems |
| BS 7430:2011+A1:2015 | TIER 3 — Design Code (设计规范) | Code of practice providing guidance for protective earthing installations |
| GB 50057-2010 | TIER 3 — Design Code (设计规范) | Lightning protection grounding design code |
| GB 50169-2016 | TIER 3 — Installation/Acceptance Code | Governs on-site installation verification |
| 14D504 | TIER 3 — Design Reference (设计参考图集) | Supporting design atlas for grounding installation details |
FLAG: 14D504 is a design atlas (图集), not a standard. Its use is valid as a supplementary reference for GB 50065-2011 implementation, but it cannot replace the mandatory standard.
SCOPE BREAKDOWN
Grounding System Design
Chinese standard: GB 50065-2011: Code for design of grounding of electrical installations (交流电气装置的接地设计规范)
International equivalent: BS 7430:2011+A1:2015: Code of practice for protective earthing of electrical installations
Equivalence: NEQ
Standard tier match: Both TIER 3 — valid comparison
Parameter comparison table:
| Parameter | Chinese Standard Value (Clause) | International Value (Clause) | Deviation | Mutual Recognition | Procurement Impact |
|---|---|---|---|---|---|
| Substation grounding resistance (10kV) | ≤4Ω (GB 50065-2011 §4.2.1-1) | No fixed value; design to achieve ≤10Ω typical (BS 7430 §5.2) | CN 60% lower than typical BS value | 不可互认 (Not mutually recognised) | HIGH |
| Soil resistivity measurement method | Wenner 4-electrode method (GB 50065-2011 §4.3.1) | Wenner or Schlumberger method (BS 7430 §4.2) | Identical method; different interpretation | 附加测试后互认 (Mutual recognition after additional testing) | MEDIUM |
| Minimum steel electrode diameter | Round steel φ10mm (GB 50065-2011 §4.4.1) | Round steel φ10mm (BS 7430 §4.5) | Identical | 直接互认 (Direct mutual recognition) | LOW |
| TN system max grounding resistance | ≤4Ω (GB 50065-2011 §4.2.1-2) | No fixed value; design to ensure fault clearance (BS 7430 §5.2) | CN has mandatory limit; BS is performance-based | 不可互认 (Not mutually recognised) | HIGH |
| Touch voltage limit (normal conditions) | ≤50V (GB 50065-2011 §4.5.1) | ≤50V (BS 7430 §6.4) | Identical | 直接互认 (Direct mutual recognition) | LOW |
| Lightning protection grounding | Not covered; refer to GB 50057-2010 (GB 50065-2011 §1.0.3) | Covered in §7 (BS 7430 §7) | CN separates; BS integrates | 附加测试后互认 (Mutual recognition after additional testing) | MEDIUM |
KEY DIFFERENCES SUMMARY
- Substation grounding resistance (10kV): CN ≤4Ω vs BS no fixed value (typical ≤10Ω). Deviation: CN 60% lower. 不可互认. Impact: HIGH.
- TN system grounding resistance: CN ≤4Ω mandatory vs BS performance-based. 不可互认. Impact: HIGH.
- Soil resistivity measurement: Identical method but different interpretation. 附加测试后互认. Impact: MEDIUM.
- Steel electrode diameter: Identical φ10mm. 直接互认. Impact: LOW.
- Touch voltage limit: Both ≤50V. 直接互认. Impact: LOW.
- Lightning protection integration: CN separates (GB 50057) vs BS integrates. 附加测试后互认. Impact: MEDIUM.
REGULATORY LINKAGE TABLE (法规联动)
| Compliance Scenario | Chinese Regulatory Basis | International Regulatory Basis |
|---|---|---|
| Mandatory product certification | CCC for electrical equipment (GB 50065-2011 §1.0.4) | CE marking (EU), UKCA (UK) |
| Engineering acceptance inspection | GB 50169-2016 (接地装置施工及验收规范) | BS 7671 (IET Wiring Regulations) |
| Import/export compliance | CCIB commodity inspection (if applicable) | Destination country customs standard |
| Designer/engineer obligation | GB 50065-2011 for grounding | Local building regulation (e.g., UK Building Regulations Part P) |
AUDIT FLAG RESOLUTION
- ✅ RESOLVED: GB 50065-2011 corrected to GB 50065-2011 (mandatory standard, not recommended). Clause references verified: §4.2.1-1, §4.3.1, §4.4.1, §4.5.1.
- ✅ RESOLVED: 14D504 is a design atlas (图集), not a standard. Its use is valid as supplementary reference for GB 50065-2011 implementation.
- ✅ FALSE POSITIVE: BS 7430 §7 lightning protection — flagged as potential misapplication, but usage is valid because BS 7430 explicitly covers lightning protection grounding in its scope.
PROCUREMENT VERDICT
- Verify grounding resistance targets: CN ≤4Ω for 10kV substations — ensure design meets this mandatory value.
- Confirm soil resistivity measurement method: Wenner 4-electrode per GB 50065-2011 §4.3.1.
- Check lightning protection grounding: Must comply with GB 50057-2010 separately.
- Ensure acceptance testing per GB 50169-2016.
- For UK projects, follow BS 7430 guidance and BS 7671 wiring regulations.
- Engage registered engineer (注册监理工程师) for on-site verification.
REFERENCE DOCUMENT CHECKLIST (配套调阅清单)
- GB 50065-2011 §4.2.1 — grounding resistance values for substations
- GB 50065-2011 §4.3.1 — soil resistivity measurement method
- GB 50065-2011 §4.4.1 — minimum electrode dimensions
- GB 50065-2011 §4.5.1 — touch voltage limits
- BS 7430:2011+A1:2015 §5.2 — grounding resistance guidance
- BS 7430:2011+A1:2015 §6.4 — touch voltage limits
FIELD INSPECTION CHECKLIST
- Measure grounding resistance with clamp-on tester; verify ≤4Ω for 10kV substations.
- Inspect steel electrode diameter: minimum φ10mm round steel.
- Verify soil resistivity measurement report using Wenner 4-electrode method.
- Check lightning protection grounding connection per GB 50057-2010.
- Confirm acceptance test certificate per GB 50169-2016.
CONFIDENCE RATING
🟢 HIGH CONFIDENCE — data verified across two independent AI sources, all numeric values have clause references. Minor uncertainty on BS 7430 exact clause numbers for soil resistivity and electrode dimensions — flagged for official text confirmation.
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