Electrical testing
Power-frequency withstand, lightning impulse, partial discharge, DC resistance, temperature rise, thermal cycling and power characteristics on fittings, cables and switchgear.
Electrical test scope
CNAS L7721 accredited · ILAC-MRA recognised
CNAS-accredited testing for HV/LV power system electrical equipment
The high voltage electrical testing centre of Yonggu Group — an accredited laboratory covering power cables and wires, power fittings, cable accessories, insulators and surge arresters, and HV/LV electrical products: pole-mounted vacuum circuit breakers, disconnectors, load-break switches, fuses and pole-mounted substation assemblies. We test to IEC, GB and EN standards and issue English-language reports that hold up to utility specifications, tender requirements and customs review.
Accreditation & recognition
CNAS L7721
ISO/IEC 17025:2017
ILAC-MRA mutual recognition
Accredited since 2015
Yonggu Group · since 1985
What we do
Five test disciplines, one accredited quality system
Six dedicated laboratories and one sample flow — from reception and identification through testing to report issue, under ISO/IEC 17025:2017.
Mechanical testing
Failing load, slip load, tensile and fatigue testing to the load defined in the standard — including a 600 kN servo-hydraulic horizontal tensile machine for long fittings.
Mechanical test scopeMaterial analysis
Chemical composition by OES, handheld XRF and SEM with EDS; metallography under a ZEISS microscope; coating mass and microstructure of aluminium and copper products.
Material test scopeAgeing & environment
Heat ageing in controlled ovens and xenon-arc ageing for insulation, sheath compounds and polymer components — the tests that decide service life in tropical and desert climates.
Ageing test scopeNDT & failure analysis
X-ray digital radiography, dye penetrant, ultrasonic and magnetic inspection — plus failure analysis after a claim, with a technical report suitable for negotiation or insurance.
NDT & analysisNot sure which test applies?
Send us the product drawing and the standard quoted in your tender. An engineer replies with a test plan, sample requirement, price and lead time within one working day.
Ask the laboratory
Why the reports are accepted
Evidence that survives scrutiny
For an export project, a test report is only useful if the buyer, the utility and the customs authority accept it. The laboratory is accredited by CNAS and its scope sits inside the ILAC Mutual Recognition Arrangement, so results travel.
- Testing accredited to ISO/IEC 17025:2017 under CNAS L7721
- Mutual recognition through CNAS as a signatory of ILAC-MRA
- English reports with clause-by-clause results and stated measurement uncertainty
- Instrument traceability held for every test in the report
- Online verification for every report number issued
- One named engineer per project, from enquiry to after-sales
Group backing
The laboratory belongs to Yonggu Group, a manufacturer of transmission and distribution materials and HV/LV electrical products founded in 1985 — which is why the test benches, the metallurgy and the failure analysis are in house rather than outsourced.
1985
Group founded in Yueqing, Zhejiang
4
International standards co-authored
100+
Patents held by the group
2015
Year the laboratory was first accredited
The laboratory sits inside the manufacturer's technology centre, and is organised so that testing answers to the quality system, not to the sales department. What this means for the standing of a report is set out plainly on the accreditation page.
Lead times
Typical turnaround
Excluding sample transport. Express slots are available for tender deadlines — ask before you ship.
| Test package | Working days | Express |
|---|---|---|
| DC resistance & dimensional check (fittings, conductors) | 5 | 3 |
| LV cable routine tests (conductor resistance, dimensions, voltage test) | 7 | 5 |
| MV cable type test (partial discharge, 4 h voltage test, insulation thickness) | 12 | 9 |
| Mechanical failing load / slip load (fittings) | 7 | 5 |
| Temperature rise & thermal cycling (connectors, busbar) | 10 | 7 |
| Lightning impulse type test (switchgear, insulators) | 20 | 15 |
| Material composition & metallography | 7 | 5 |
| Heat ageing / xenon-arc ageing | Per standard cycle | — |
Turnaround starts when the sample and the confirmed test plan are both received. Ageing programmes run to the cycle defined in the applicable standard.
Products
What we test
The accredited scope covers roughly 200 test items across about 80 national standards, spanning power cables and line materials as well as high- and low-voltage electrical products. The families below account for most export projects.
| Product family | Main standards | Representative tests |
|---|---|---|
| Power cables & wires LV and MV XLPE / PVC power cable, ABC, bare conductors |
IEC 60502, IEC 60227, IEC 61089, GB/T 12706, GB/T 5023 | Conductor DC resistance, insulation thickness, partial discharge, AC withstand, ageing, flame propagation |
| Power fittings Tension & suspension clamps, connectors, line hardware |
IEC 61284, GB/T 2314, GB/T 14315, GB/T 9327, DL/T 2340 | Failing load, slip load, galvanising mass, metallography, DC resistance |
| Cable accessories LV and MV heat-shrink and cold-shrink terminations, joints, sealing ends, waterproof boxes (1–35 kV) |
IEC 60502, GB/T 12706, GB/T 9327 | Power-frequency withstand, partial discharge, thermal cycling, ageing |
| Insulators & arresters Composite and porcelain insulators, surge arresters |
IEC 61109, IEC 60099-4, GB/T 19519, GB/T 11032 | Power-frequency withstand, lightning impulse, mechanical failing load, ageing |
| HV switchgear & distribution apparatus Pole-mounted vacuum circuit breakers (10 & 35 kV, incl. primary-secondary integrated), disconnectors and earthing switches, load-break switches, HV fuses, enclosed switchgear, pole-mounted substation assemblies |
IEC 62271-1, IEC 62271-100, IEC 62271-102, IEC 62271-103, IEC 62271-200, IEC 60282-1, GB/T 11022, GB/T 1984, GB/T 1985, GB/T 3906, GB/T 15166 | Withstand voltage, lightning impulse, temperature rise, mechanical operation, short-time current, over-current |
| LV electrical products LV switchgear and controlgear assemblies, moulded-case and miniature circuit breakers, distribution boards and enclosures |
IEC 61439-1, IEC 60947-1, IEC 60947-2, IEC 60529, GB/T 7251.1, GB/T 14048.1, GB/T 14048.2 | Withstand voltage, temperature rise, mechanical operation, over-current, enclosure and IP checks |
| Copper & aluminium products Tube busbar, conductors, sheet and profiles |
IEC 61089, GB/T 3190, GB/T 5231, GB/T 5585 | Chemical composition, tensile strength, elongation, DC resistivity, dimensions |
Standards by country or region
Cables and wires are ordered against national standards that are not interchangeable. The table below maps the standard each market normally quotes, so the test plan can be written against the right one from the start.
| Country / region | LV power cable (0.6/1 kV) | MV power cable | Wires and building wire (450/750 V and below) |
|---|---|---|---|
| International (IEC) | IEC 60502-1 | IEC 60502-2 | IEC 60227 (PVC), IEC 60245 (rubber) |
| China (GB) | GB/T 12706.1; conductors GB/T 3956 | GB/T 12706.2, GB/T 12706.3 | GB/T 5023.1–.7, JB/T 8734, JB/T 10491 (XLPE) |
| European Union (CENELEC / HAR) | HD 603 S1 | HD 620 S1 | EN 50525-1/-2/-3 (replacing HD 21 and HD 22) |
| United Kingdom | BS 5467 (XLPE/SWA), BS 6346 (PVC/SWA), BS 6724 | BS 6622 (PVC), BS 7835 (LSZH), BS 7870-4.10 | BS EN 50525, BS 6004, BS 6500, BS 7211; fire BS 6387, BS 7629-1 |
| Germany | DIN VDE 0276-603 (= HD 603), types NAYY / NA2XY | DIN VDE 0276-620 (XLPE), 0276-621 (PVC) | DIN VDE 0281 (PVC), DIN VDE 0282 (rubber), DIN VDE 0250 (NYM-J / NYY-J) |
| France | NF C 32-321 (now XP C 32-321) = U-1000 R2V | NF C 33-226 (XLPE, 6/10 to 18/30 kV) | NF C 32-201 (H07V-U / -K) |
| Italy | CEI UNEL 35375 (FG7R / FG7OR / FG7OH1R / FG7OH2R), 35756 / 35757 (N1VV-K) | CEI 20-13 (elastomeric G7, rubber-insulated, 1–30 kV), CEI 20-89 | CEI UNEL 35752 (N07V-K), 35368 (N07G9-K) |
| Spain | UNE 21123-2 (RV-K), UNE 211435 (RZ1-K, halogen-free) | UNE 21123, UNE 211435 (MV types) | UNE 21031 (H07V-K) |
| Russia | GOST 31996-2012 (VVG / AVVG); conductors GOST 22483 | GOST R IEC 60502-2 | GOST 6323-79 (PV), GOST 7399-97 (PVS) |
| Kazakhstan | GOST 31996-2012, ST RK IEC 60502-1 | GOST R IEC 60502-2 | GOST 6323-79, GOST 7399-97 |
| Kyrgyzstan | GOST 31996-2012 | GOST R IEC 60502-2 | GOST 6323-79, GOST 7399-97 |
| Uzbekistan | O’zDSt-IEC-60502-1 | O’zDSt 2703-2021 (referring to GOST R IEC 60502-2) | GOST 6323-79, GOST 7399-97 |
| Tajikistan | GOST 31996-2012 | GOST R IEC 60502-2 | GOST 6323-79, GOST 7399-97 |
| Turkmenistan | GOST 31996-2012 | GOST R IEC 60502-2 | GOST 6323-79, GOST 7399-97 |
| North America (US and Canada) | UL 44, UL 83, ICEA S-95-658; Canada CSA C22.2 No. 75 / No. 38 | ICEA S-93-639, AEIC CS8, UL 1072; Canada CSA C22.2 No. 131 (TECK90), No. 239 | UL 83 (THHN / THWN-2), UL 62; Canada CSA C22.2 No. 75 / No. 38 / No. 49 |
| Japan and Korea | JIS C 3605 (600 V IV / HIV), KS C IEC 60502-1 | JIS C 3606 (CV), KS C IEC 60502-2 | JIS C 3307, JIS C 3662, KS C IEC 60227 |
| Australia and New Zealand | AS/NZS 5000.1 | AS/NZS 1429.1 | AS/NZS 5000.2, AS/NZS 3191 (flexible cords), AS/NZS 1125 (conductors) |
| India | IS 1554-1 (PVC), IS 7098-1 (XLPE) | IS 7098-2 | IS 694, IS 8130 (conductors) |
| Brazil | ABNT NBR 7288 | ABNT NBR 6251 | ABNT NBR NM 247-3 / -5, NBR 13248 (XLPE 0.6/1 kV) |
| South Africa | SANS 1507 | SANS 1339 | SANS 1507 series |
| Middle East and Türkiye | IEC 60502-1 / BS 5467 as called up by SASO, ESMA and DEWA; TS IEC 60502-1 (NYY) | IEC 60502-2 / BS 6622; TS IEC 60502-2 | BS EN 50525, TS EN 50525, TS IEC 60227 (NYA / NYAF) |
Voltage classes used above
| Class | Range | Main standards |
|---|---|---|
| Low voltage | Up to 1 kV — 0.6/1 kV in most systems; a 600 V class applies in North America and Japan | IEC 60502-1 |
| Medium voltage | 3.6/6, 6/10, 8.7/15, 12/20, 18/30 and 26/35 kV | IEC 60502-2 |
| High voltage | Above 36 kV | IEC 60840, IEC 62067 |
The medium-voltage boundary moves with the system: roughly 6–30 kV under IEC and GB, 6.6–33 kV under BS, 5–46 kV under IEEE. Tell us which system the tender uses and we will quote against that definition.
North American building wire (600 V class)
The 600 V class is a parallel system to IEC 0.6/1 kV, not an equivalent one: it applies the same limit to line-to-earth and line-to-line, and it has no 3.5 kV / 5 min routine withstand test, relying instead on spark testing and UL follow-up service. Letter code: T thermoplastic · H 75 °C · HH 90 °C · W wet location · N nylon jacket · “2” wet-rated 90 °C.
| Designation | Insulation | Dry | Wet | Standard | Note |
|---|---|---|---|---|---|
| TW | PVC | 60 °C | 60 °C | UL 83 | Older type, being phased out |
| THW / THW-2 | PVC | 75 / 90 °C | 75 / 90 °C | UL 83 | — |
| THHN | PVC + nylon | 90 °C | 75 °C | UL 83 | The most frequent selection error — the wet rating drops to 75 °C |
| THWN / THWN-2 | PVC + nylon | 75 / 90 °C | 75 / 90 °C | UL 83 | Usually dual-marked “THHN/THWN-2” |
| XHHW / XHHW-2 | XLPE | 90 °C | 75 / 90 °C | UL 44 | Thinner insulation, so more conductors fit the same raceway |
| RHW / RHW-2 | XLPE | 75 / 90 °C | 75 / 90 °C | UL 44 | Available for 600 V or 2 kV |
| RHH | Thermoset | 90 °C | Not rated | UL 44 | Dry locations only |
| SA / Z / FEP | Silicone rubber / special | 200 / 150 °C | Dry only | UL 44, UL 83 | Special applications |
Canadian designations (CEC / CSA)
| Designation | Standard | Note |
|---|---|---|
| T90 | CSA C22.2 No. 75 (equivalent to UL 83) | PVC + nylon; 90 °C dry, 75 °C wet, 60 °C oil; installable down to −10 °C |
| TW75 | CSA C22.2 No. 75 | Single-core PVC, 75 °C |
| RW90 / RWU90 | CSA C22.2 No. 38 (equivalent to UL 44) | XLPE; 90 °C dry and wet; −40 °C; RWU90 is 1 kV and may be direct-buried |
| NMD90 / NMWU90 | CSA C22.2 No. 48 | Non-metallic sheathed; 300 V only, not the 600 V of US NM-B |
| AC90 / ACG90 / ACWU90 | CSA C22.2 No. 51 | Armoured |
| TECK90 | CSA C22.2 No. 131 | Industrial armoured, 1000 V / 90 °C, FT4, −40 °C |
| USEI90 / USEB90 | CSA C22.2 No. 52 | Service entrance cable |
| TC / TC-ER, CIC | CSA C22.2 No. 239 | Tray cable and instrumentation cable |
Related US standards: UL 854 (SE / USE service entrance cable) · UL 719 (NM-B, 600 V) · UL 1063 (MTW machine-tool wire) · UL 62 (flexible cord) · ICEA S-95-658 / NEMA WC 70 for 0.6/1 kV power cable construction.
Points that change the answer
- Ampacity basis. NEC Table 310.16 assumes a 30 °C ambient, no more than three current-carrying conductors, in raceway or cable tray, and gives separate 60 / 75 / 90 °C columns; 110.14(C) (the column is chosen by terminal temperature) and 240.4(D) (15 A for 14 AWG, 20 A for 12 AWG, 30 A for 10 AWG) both limit what the table appears to allow. IEC 60364-5-52 and GB 16895 instead use 30 °C air and 20 °C soil with installation-method tables, then apply correction factors for ambient temperature, grouping and soil thermal resistivity.
- Cross-section systems. North America uses AWG / kcmil, IEC uses mm². Any conversion has to state whether it is an equivalent or an actual cross-section — 12 AWG and 4 mm² are not the same conductor.
- Flame retardancy. US practice (VW-1, FT1, FT4, IEEE 1202, UL 1685) and IEC / European practice (IEC 60332-1, IEC 60332-3, EN 50575 CPR classes Eca to B2ca) are separate systems and are not mutually recognised, so each has to be demonstrated on its own terms.
- Central Asia. Grid projects there usually also call up GOST 31565-2012 (fire safety requirements for cables) and GOST 22483 (conductors, equivalent to IEC 60228).
Installation codes quoted alongside
BS 7671 (18th edition, UK) · REBT and ITC-BT (Spain) · CEI 64-8 (Italy) · NF C 15-100 (France) · DIN VDE 0100 (Germany) · GB 50054 (China) · PUE (Russia and Central Asia) · NEC / NFPA 70 and CSA C22.1 (North America) · AS/NZS 3000 (Australia and New Zealand) · NBR 5410 (Brazil) · SANS 10142-1 (South Africa).
The standard numbers on this page identify the specification a product is ordered against; they are not by themselves an accredited test item. The accredited schedule lists Chinese national (GB) standards, and equivalent IEC, EN and other national methods are carried out under the same quality system and identified separately in the report. Send us the standard the buyer quotes and we will confirm, item by item, what is inside the accredited scope and what is not.
How it works
From enquiry to report
1
Send the requirement
Product drawing or datasheet, the standard quoted by the buyer, quantity and deadline. Use the online enquiry form or email.
2
Confirm the test plan
We reply with the test items, sample quantity, price and lead time, and state clearly whether each item is inside the accredited scope.
3
Ship the sample
Mark the parcel as a test sample with no commercial value and quote the test plan number. Reception photographs and bar-codes the sample on arrival.
4
Testing and technical review
The sample is routed to the relevant laboratory. Every result is reviewed against the clause of the standard before the report is released.
5
Report and verification record
A signed PDF is issued first, followed by the original by courier. The report number resolves in the online verification tool.
Have a tender deadline?
Send us the standard and the sample list. We will tell you within one working day what can be done, how long it takes and what it costs.