Type-test evidence and standards: DL/T 1312, IEEE 80, UL 467, IEC 62561-2
Our products are type-tested to DL/T 1312-2023 – the Chinese electric-power industry standard for copper-clad steel earthing conductor, issued by the National Energy Administration, and the only standard we know of that qualifies horizontal earthing conductor under power-frequency fault current and a life-cycle corrosion sequence (item-by-item comparison with UL 467 and IEC 62561-2 at the end of this page). A series of type-test reports issued by a laboratory holding both CMA (China Metrology Accreditation, the statutory mark for legally valid test data in China) and CNAS accreditation, stamped with both marks and carrying the ILAC-MRA symbol, covers Ø 12–18 horizontal conductor and Ø 20 / 25 rods at 0.25, 0.6 and 0.8 mm copper. Under the ILAC mutual-recognition arrangement, accreditation bodies in more than 100 economies recognise one another's accreditation, which facilitates acceptance of the reports; whether a report is accepted remains the decision of each project owner and reviewer.
| Ø | 0.25 mm | 0.6 mm | 0.8 mm | |
|---|---|---|---|---|
| Horizontal conductor | 12 | ✓ | ✓ | — |
| 14 | — | — | ✓ | |
| 16 | ✓ | ✓ | — | |
| 18 | — | — | ✓ | |
| Vertical rod | 20 | — | — | ✓ |
| 25 | — | — | ✓ |
Each report covers the full DL/T 1312-2023 programme: copper thickness at any point (minimum of 9 / 12 points), surface, tensile strength (≥ 300 N/mm² horizontal / ≥ 550 vertical), bend test (horizontal 90° × 3 / vertical 30° × 20), copper–steel bond (torsion / hammer), resistivity and conductivity grade, power-frequency high current (90% of fusing current × 3, ΔR ≤ 5%), and the electrical and corrosion sequence (ΔR ≤ 10% per stage, ≤ 30% overall). Sizes outside the matrix – including the Ø 16 / 0.8 mm this site leads with, and every 1.0 mm size – have not been type-tested; we say so plainly. The reason is cost and time: one full DL/T 1312 sequence (25 current–temperature cycles, 10 freeze–thaw cycles, 500 h salt spray, three high-current shots) typically takes about two months, and no manufacturer in the industry runs it size by size. The process, the copper–steel bond and the methods for measuring copper thickness and resistivity are the same for every size; the matrix covers Ø 12–25 across three copper classes, and the technical data for sizes outside it are calculated values. Our commitment: under clause 8.2 of the standard, whichever size your project needs a report for, we will test it – the full DL/T 1312 programme, and on request the IEC 62561-2 / UL 467 methods as well, at a CNAS-accredited laboratory. Cost: free of charge for orders of US$ 30,000 and above; below that the customer pays the laboratory fee up front and it is credited in full against the order. Timing is stated with the quotation. Full original reports and English summaries are available to project parties on request.
- Tested against substation-level fault current. The DL/T 1312-2023 electrical and corrosion sequence is: 25 current–temperature cycles at 350 °C (1 h hold each) → 10 freeze–thaw cycles → at least 500 hours of 5 % salt spray → three power-frequency fault-current shots at 90 % of the 4 s or 10 s fusing current, with resistance measured at every stage (≤ 10 % rise per stage, ≤ 30 % overall). It qualifies the conductor for a lifetime of power-frequency fault current in corrosive ground, not just the appearance of a coating.
- Same equations your consultant uses. The thermal-stability and fusing-current formulae in DL/T 1312-2023 are IEEE Std 80-2013 eq. (37) with the CCS constants of Table 1; the sequential test method is modelled on IEEE Std 837 (a connector standard) and applied here to the conductor. The Chinese standard family (GB/T 50065, DL/T 1312, DL/T 2727, DL/T 2650) has been aligned with IEEE 80 from the national benchmark code down.
- ISO 9001 factory with batch traceability from raw copper and steel to finished coil.
- Verify on receipt: micrometer and coating gauge at three sections; cross-section sample for visual / metallographic check; bend and bond tests. Send a sample to any accredited lab of your choice – if it disagrees with our data sheet, we prepay the second test.
Report list
Each report is issued by a laboratory holding both CMA and CNAS accreditation, stamped with both marks and the ILAC-MRA combined mark. Model codes follow the DL/T 1312 format (process – conductivity grade – copper – size); report numbers, dates and English summaries are available on request and will be entered line by line before launch. Conductivity grades shown are indicative; the report governs.
| Size tested | Model code (DL/T 1312 format) | Standard and scope | Report no. / date | Laboratory | English summary |
|---|---|---|---|---|---|
| Ø 12 horizontal, 0.25 mm | CCS EP 15-0.25-Φ12 | DL/T 1312-2023 full programme | on request | on request | Request |
| Ø 12 horizontal, 0.6 mm | CCS CC 20-0.6-Φ12 | DL/T 1312-2023 full programme | CT2025070054-CPB01 · tested Aug 2025, English edition issued 13 Aug 2026 | Marine Equipment Inspection & Testing Co. (National Center, Shandong; CNAS L10793) | Download report (English) |
| Ø 14 horizontal, 0.8 mm | CCS CC 20-0.8-Φ14 | DL/T 1312-2023 full programme | on request | on request | Request |
| Ø 16 horizontal, 0.25 mm | CCS EP 15-0.25-Φ16 | DL/T 1312-2023 full programme | on request | on request | Request |
| Ø 16 horizontal, 0.6 mm | CCS CC 20-0.6-Φ16 | DL/T 1312-2023 full programme | on request | on request | Request |
| Ø 18 horizontal, 0.8 mm | CCS CC 20-0.8-Φ18 | DL/T 1312-2023 full programme | on request | on request | Request |
| Ø 20 rod, 0.8 mm | CCS CC 20-0.8-Φ20 | DL/T 1312-2023 full programme | on request | on request | Request |
| Ø 25 rod, 0.8 mm | CCS CC 15-0.8-Φ25 | DL/T 1312-2023 full programme | on request | on request | Request |
Sizes outside the matrix (including Ø 16 / 0.8 mm and every 1.0 mm size): calculated values, type-tested on request for a project – the rule is set out below.
Measured data: Ø 12 / 0.6 mm continuous-cast wire, report CT2025070054-CPB01
Three samples, tested 7 Jul – 21 Aug 2025, judged against DL/T 1312-2023 type CCS CC 20-0.6-Φ12 (horizontal electrode). Every item passed; the full report (English, 8 pages) is downloadable.
| Item | Requirement | Sample 1 / 2 / 3 | Verdict |
|---|---|---|---|
| Diameter | 12.00–12.35 mm | 12.04 / 12.04 / 12.04 | Pass |
| Copper layer (minimum) | ≥ 0.60 mm | 0.60 / 0.61 / 0.60 | Pass |
| Tensile strength | ≥ 300 N/mm² | 484 / 489 / 484 | Pass |
| 90° bend × 3 | no cracks or pits in the copper | Pass | Pass |
| Bond test | no separation of copper from steel | Pass | Pass |
| Resistivity / conductivity | ≤ 8.62 × 10⁻⁸ Ω·m / ≥ 20 % | 5.63 × 10⁻⁸ Ω·m / 31 % IACS (0.494 Ω/km) | Pass |
| Current-temperature cycling (350 °C × 1 h × 25) | ΔR ≤ 10 % | +1 / +1 / +1 % | Pass |
| Freeze-thaw (−10 °C / 20 °C × 10) | ΔR ≤ 10 % | −1 / −0.4 / −1 % | Pass |
| Neutral salt spray (5 % NaCl, 500 h) | ΔR ≤ 10 %, no blisters or cracks | +1 / +0.2 / +1 %, surface pass | Pass |
| Power-frequency high current (5.38 kA × 10 s × 3) | ΔR ≤ 10 % | −1 / −0.4 / −1 % | Pass |
| Final resistance change after the sequence | ≤ 30 % | +0.4 / +0.2 / +0.2 % | Pass |
31 % IACS sits inside the 15–40 % range stated on this site; for thermal sizing use the measured value from the report. 5.38 kA is 90 % of the 10 s fusing current of this size – a substation-fault-current test, not a coating inspection.
Technical requirements and type-test programme (per DL/T 1312-2023)
DL/T 1312-2023 is a Chinese electric-power industry standard issued by the National Energy Administration, written specifically for copper-clad steel earthing conductor; it covers every form, horizontal and vertical, and qualifies the conductor under power-frequency fault current and a 500-hour salt-spray sequence – far more demanding than UL 467 (an equipment listing standard with no copper-thickness or corrosion-life test for horizontal conductor) or IEC 62561-2 (a lightning-protection component standard with no fault-current test). The item-by-item comparison follows below. Our type-test reports are issued against the full programme of this standard; the table gives the acceptance limits of clause 6 and the test methods of clause 7.
| Item | Requirement (clause 6) | Test method (clause 7) |
|---|---|---|
| Copper thickness | Minimum at any measuring point ≥ nominal (0.25 / 0.60 / 0.80 mm or custom); nominal not below 0.25 mm | Rod and wire: 3 positions ≥ 50 mm from the end, 3 points at 120° each – 9 points; tape: 3 positions × 4 points – 12 points; minimum value taken. Magnetic method GB/T 4956 or microscope GB/T 6462 |
| Surface | Fine, uniform, smooth; no pinholes, pits, blisters, peeling, cracks or burns; no bare steel, loose copper or black spots | Visual, magnifier where needed |
| Tensile strength | Horizontal electrode and bonding conductor ≥ 300 N/mm²; vertical electrode ≥ 550 N/mm² | GB/T 228.1, specimen ≥ 500 mm between grips |
| Bending | No cracks, fissures or pits in the copper after bending | Horizontal / conductor: 90° ± 5°, 3 bends; vertical: 30° ± 5° at 40 diameters from the clamp, 20 bends |
| Bond | No separation of copper from steel; strand wires show no cracks, flaking or holes after torsion | Strand wire: torsion to fracture per GB/T 239; other products: one end cut to a 45° cone, copper hammered off, interface inspected |
| Resistivity / conductivity | By grade: 15 / 20 / 25 / 30 / 40% IACS (resistivity at 20 °C not above 11.50 / 8.62 / 6.90 / 5.75 / 4.31 ×10⁻⁸ Ω·m); special grades not below nominal and ≥ 15% | GB/T 3048.2 / 3048.4, 1 m specimen, corrected to 20 °C with 0.00378 /°C |
| Power-frequency high-current withstand | No blistering, cracking or melting; resistance change ≤ 5% | 90% of the 4 s or 10 s fusing current calculated per Annex C, applied 3 times, cooled below 100 °C between shots |
| Electrical and corrosion performance | Resistance increase ≤ 10% at each stage, ≤ 30% overall; no blistering, cracking or melting throughout | Sequence: current–temperature cycling (350 ± 10 °C held 1 h, ≥ 25 cycles) → freeze–thaw (≤ −10 °C / ≥ 20 °C, 2 h each, 10 cycles) → neutral salt spray (5% NaCl, ≥ 500 h) → power-frequency high current (90% of fusing current × 3); resistance measured before and after each stage |
Inspection rules (clause 8): type tests are run before a new product enters production, on a change of material or process, on restart after six months, every three years, or at the customer's request – a size specified by the customer can be type-tested and reported on that basis. Routine tests are per lot (same type, size and temper, ≤ 5000 m per lot) with copper thickness and surface checked reel by reel. Supply comes with the type-test report and raw-material inspection report; each consignment carries the instructions, routine test report and certificate of conformity.
What DL/T 1312-2023 is, and how it compares with UL 467 and IEC 62561-2
DL/T standards are China's electric-power industry standards, issued by the National Energy Administration and applied to earthing materials in generation, transmission and distribution projects. DL/T 1312-2023 is the dedicated product standard for copper-clad steel earthing conductor; State Grid's corporate standard Q/GDW 10466 is essentially aligned with it. The two standards an overseas engineer knows best address different things: UL 467 is a listing standard for grounding and bonding equipment – rods, plates, mesh, clamps, connectors, exothermic kits – and sets no copper-thickness or corrosion-life requirement for horizontal earthing conductor; IEC 62561-2 is a lightning-protection component standard, designed around lightning duty, with no power-frequency fault-current test and salt-spray exposure measured in days. Side by side:
| Item | UL 467-2022 (US) | IEC 62561-2:2025 (Europe / IEC) | DL/T 1312-2023 (China, power industry) |
|---|---|---|---|
| Nature | Safety listing standard for grounding and bonding equipment | Lightning protection system components: conductors and earth electrodes | Dedicated product standard for copper-clad steel in power-engineering earthing |
| Products covered | Grounding and bonding equipment: rods, plates, mesh, clamps, connectors, exothermic kits; conductor material by reference to ASTM specifications | LPS conductors and earth electrodes, including copper coated steel rods and conductors | CCS rods, tape, round wire and strand – horizontal and vertical alike |
| Horizontal earthing conductor | Not covered | Covered, as LPS conductor | Covered, with power-frequency fault-current and life-cycle corrosion requirements |
| Minimum copper thickness | Rods ≥ 0.254 mm at any point | Rods ≥ 250 µm; conductors ≥ 70 µm | 0.25 / 0.60 / 0.80 mm or custom by soil corrosivity, minimum at any of 9 / 12 measuring points |
| Bond and bending | Adhesion test; 30° bend | Visual and adhesion check of coating after environmental test | Horizontal 90° × 3, vertical 30° × 20 with no cracks in the copper; torsion to fracture / 45° hammer test with no separation |
| Tensile strength | Not specified | By material class | Horizontal ≥ 300, vertical ≥ 550 N/mm², specified separately |
| Conductivity | Not specified | Specified by material and cross-section; no conductivity grade | Five grades 15–40% IACS, measured on every lot |
| Power-frequency fault-current test | None | None (designed around lightning impulse duty) | 90% of the 4 s or 10 s fusing current, 3 shots, ΔR ≤ 5% |
| Current–temperature cycling | None | None | 350 ± 10 °C held 1 h, ≥ 25 cycles |
| Freeze–thaw | None | None | ≤ −10 °C / ≥ 20 °C, 2 h each, 10 cycles |
| Salt-spray corrosion | None | About 3 days of salt mist (IEC 60068-2-52 severity 2) plus humid sulphurous atmosphere, assessed visually | 5% NaCl neutral salt spray ≥ 500 h (about 21 days), assessed by resistance change |
| Acceptance basis | Construction and thickness checks | Visual, thickness and adhesion after test | Resistance rise ≤ 10% per stage and ≤ 30% over the sequence, plus appearance – quantified |
| Routine / acceptance testing | Factory follow-up inspection after listing | Type test + manufacturer's declaration of conformity (CE marking within the EU) | Type test + routine test on every lot (≤ 5000 m, copper thickness on every reel) + buyer's acceptance test |
The three address different duties and do not replace one another: UL 467 asks "can this rod be listed?", IEC 62561-2 asks "will this conductor survive a lightning strike?", DL/T 1312-2023 asks "will this conductor survive substation fault current and thirty years in the ground?". For the technical requirements on a power-earthing conductor – above all a horizontal one – DL/T 1312-2023 is the one of the three with the most complete coverage and the most test items. Specific UL 467 and IEC 62561-2 clauses should be read in their current editions. For HV substation earthing in Europe the governing design standard is EN 50522 / IEC 61936-1 (cross-section by fault current, with minimum electrode dimensions in its annex that distinguish copper-sheathed from electroplated steel) – for substation submittals we provide the mapping to that standard as well.
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