When ordering MV or LV switchgear from China, send a complete technical specification, require type-test reports to IEC 62271-200 (MV) or IEC 61439 (LV) that match your exact design, approve drawings before manufacture, and witness a factory acceptance test before shipment. This checklist covers each step in the order a project buyer meets it.
1. Spec sheet: what to send with the enquiry
An incomplete enquiry is the main reason quotes cannot be compared. Send these items for every switchboard.
| Item | MV switchgear | LV switchgear |
|---|---|---|
| Rated voltage | Rated voltage of the equipment (for example 12 kV, 24 kV, 36 kV) and system voltage | Rated operational voltage and rated insulation voltage |
| Rated frequency | 50 or 60 Hz | 50 or 60 Hz |
| Busbar current | Rated normal current of main busbar | Rated current of the assembly and of each circuit |
| Short-circuit | Rated short-time withstand current and duration (for example 25 kA for 3 s), and peak withstand current | Rated short-time withstand current (Icw) and peak (Ipk), or conditional short-circuit current |
| Insulation | Power-frequency and lightning impulse withstand levels | Rated impulse withstand voltage |
| Enclosure | IP code to IEC 60529, indoor or outdoor | IP code, form of internal separation (Form 1 to Form 4) |
| Arc | IAC classification (see section 3) | Arc-fault requirements if specified by the client |
| Switching device | Vacuum or SF6 circuit breaker, load-break switch, fuses; withdrawable or fixed | ACB, MCCB, MCB; withdrawable, plug-in or fixed |
| Protection | Relay functions, CT and VT ratios and classes | Breaker trip units, metering, earth-leakage |
| Environment | Altitude, ambient temperature, humidity, pollution | Altitude, ambient temperature, humidity |
| Control | Auxiliary voltage (AC/DC), interlocks, SCADA protocol | Auxiliary voltage, communication, motor control needs |
Also list the single-line diagram, panel count and functions, cable entry (top or bottom), cable size and number per phase, and any client or utility specification that overrides the standard.
2. Standards to name in the order
- MV metal-enclosed switchgear: IEC 62271-200, with IEC 62271-1 for common specifications.
- MV circuit breakers: IEC 62271-100; disconnectors and earthing switches: IEC 62271-102.
- LV switchgear and controlgear assemblies: IEC 61439-1 and IEC 61439-2 for power switchgear assemblies.
- LV circuit breakers inside the assembly: IEC 60947-2.
- Instrument transformers: IEC 61869 series.
- Quality system: ISO 9001 for the manufacturer.
For MV, also specify the loss of service continuity category (LSC1, LSC2, LSC2A or LSC2B) and the partition class (PM for metallic, PI for insulating) as defined in IEC 62271-200.
3. IAC classification
Internal arc classification (IAC) under IEC 62271-200 states whether the switchgear has been tested to protect people near it during an internal arc. Specify all four parts:
- Accessibility type: A (authorised personnel only) or B (general public).
- Accessible sides: F (front), L (lateral), R (rear), for example AFLR.
- Arc fault current: in kA.
- Arc duration: in seconds.
Check that the IAC in the test report matches the room layout. A board tested as AF only must not be installed with rear access for staff. Ask how the arc gases are vented (into the room, into a duct, or out of the building) and whether the duct was part of the test.
4. Type tests vs routine tests
| Type tests | Routine tests | |
|---|---|---|
| Purpose | Prove the design meets the standard | Check each unit was built correctly |
| Done on | One representative unit of the design | Every unit delivered |
| Where | Usually an independent high-power laboratory | Manufacturer's factory |
| Examples (MV) | Dielectric, temperature rise, short-time and peak withstand, making and breaking, mechanical operation, IP, IAC | Power-frequency voltage test of main circuit, auxiliary circuit tests, resistance of main circuit, mechanical operation |
| Examples (LV) | Design verification under IEC 61439: temperature rise, short-circuit withstand, dielectric, clearances, IP | Routine verification: wiring, insulation, dielectric, function |
Check that each type-test report covers your rating and configuration: the same voltage, current, short-circuit level, enclosure and switching device. A report for a 25 kA panel does not cover an order for 31.5 kA. Ask for the full report, not just the certificate page, and check the laboratory name and report number.
5. Drawings approval
Make drawing approval a contract milestone before manufacture starts.
- General arrangement: dimensions, weight, front view, cable entry and floor fixing.
- Single-line diagram with every device and rating.
- Schematic and wiring diagrams for protection and control.
- Bill of materials with make and model of breakers, relays, CTs, VTs and meters.
- Nameplate and labelling text in the required language.
Mark up, return and receive a revised set marked "approved for construction". Late changes after this point cost time and money.
6. What to check with a Chinese supplier
Confirm the company makes the switchgear itself rather than reselling another factory's panels, by checking its Unified Social Credit Code in the national enterprise credit system and its business scope. Ask whether type-tested designs are its own or licensed, and get the type-test reports in the manufacturer's name. Request ISO 9001 certification and, for the domestic market, any CCC certificate for LV products it covers. Our category scores reflect verifiable company data, not product quality; see the methodology for what is measured. Start with the ranked lists of switchgear, high-voltage switchgear and ring main units manufacturers.
7. Factory acceptance test (FAT)
Agree the FAT procedure with the drawings, then witness it in person or by video.
- Visual and dimensional check against approved drawings.
- All routine tests from the relevant standard, with recorded results.
- Mechanical operation of breakers, switches and interlocks, including racking of withdrawable units.
- Secondary injection of protection relays and check of trip circuits.
- Functional test of control, metering and SCADA signals.
- Check of nameplates, labels, earthing and the spare parts list.
Sign the FAT report and a list of open points. Release shipment only after open points are closed.
8. Packing and shipping
- Ship each panel or transport section upright, fixed to a skid, wrapped against moisture with desiccant inside.
- Use seaworthy wooden cases for sea freight; mark centre of gravity, lifting points and "this way up".
- Remove or block withdrawable breakers and heavy devices as instructed by the manufacturer.
- Pack busbar links, bolts and site parts separately with a labelled list.
- Fit shock and tilt indicators on large sections.
- Include the installation manual, test reports and as-built drawings in the shipment and by email.
Related items such as vacuum circuit breakers, moulded-case circuit breakers and distribution cabinets are ranked separately if you buy them loose.
Frequently asked questions
Which standard applies to LV switchboards?
IEC 61439 applies to low-voltage switchgear and controlgear assemblies; part 1 covers general rules and part 2 covers power switchgear assemblies. The breakers inside are usually tested to IEC 60947-2.
What does IAC AFLR mean?
It means the switchgear is classified for access by authorised personnel only (A) and was arc-tested on the front, lateral and rear sides (F, L, R). The arc current and duration must also be stated.
Is a type-test certificate enough?
No. Ask for the full type-test report and check that it covers your voltage, current, short-circuit rating and panel design. Routine tests must also be done on every unit you receive.
Should I attend the FAT?
Yes, or send a qualified inspector. The FAT is the last point where defects can be fixed cheaply before shipment.