Service · Factory execution · FAT
Switchgear & control panel FAT witnessing in China
Switchgear and control panels fail quietly: the cabinet looks finished, the certificate says passed, and the mis-wired CT circuit or dead interlock only announces itself at site. Sinospect's engineers witness the FAT at the Chinese factory against your drawings and schedule of tests — construction and wiring verification, dielectric and continuity tests, mechanical operations and interlocks, protection and control function by simulation — and issue a signed witness record with a clear release, hold or retest recommendation before anything is packed.
- Equipment class
- LV/MV switchgear, MCCs, control cabinets, automation and instrumentation panels
- Test basis
- IEC 61439 / IEC 62271 as applicable, approved drawings and your schedule of tests
- Where it runs
- Panel builders' and switchgear manufacturers' workshops across China
- Engagement output
- Signed witness record, non-conformity log and release recommendation
Quick answers
What does switchgear FAT witnessing in China cover?
An independent engineer verifies the assembly against approved drawings, then witnesses the routine tests — protective-circuit continuity, insulation and dielectric withstand, mechanical operations, interlocks — and the functional checks of controls, metering and protection agreed in the test schedule. Results are recorded against acceptance criteria in a signed witness record; the buyer keeps the release decision.
| Test group | What is witnessed | Acceptance basis |
|---|---|---|
| Construction and wiring | Assembly against approved drawings, point-to-point wiring, terminations, labelling, clearances and creepage | Approved schematics and IEC 61439 / IEC 62271 as applicable |
| Electrical routine tests | Protective-circuit continuity, insulation resistance, dielectric withstand | Product standard and purchase specification |
| Mechanical and interlocks | Operating cycles, racking, earthing switch, interlock logic, door and key interlocks | Test schedule and manufacturer procedure |
| Protection and control function | Secondary injection of relays, control logic, alarms, metering and indication by simulation | Settings file, logic diagrams and the agreed schedule of tests |
| Documentation | Routine-test certificates, settings records, as-built markups, manuals | Contract document list |
Why witness a panel FAT instead of fixing problems at site?
Because the same defect costs hours at the factory and days at site: a mis-wired CT circuit, a failed interlock or a wrong label is corrected on the shop floor before packing, but becomes an outage, a variation order or a safety event after installation. The witnessed FAT is the last point where correction is entirely the supplier's problem.
| Defect found | At the witnessed FAT | At site |
|---|---|---|
| Wiring error in a protection circuit | Re-terminated and re-verified the same day | Fault-finding under schedule pressure, possible re-energization delay |
| Interlock fails its sequence | Adjusted and re-witnessed before packing | Safety observation, site rework, acceptance dispute |
| Missing settings or as-built records | Logged as an open item blocking release | Commissioning delay while documents are chased across time zones |
01 · Scope
When switchgear FAT witnessing is the right control
Panel-shop quality lives in the details a photograph cannot prove: torque on a busbar joint, the routing of a CT circuit, whether the interlock actually prevents the unsafe sequence or merely exists on the drawing. Once panels are packed, every remaining error is discovered at site — cabled in, energized, and under commissioning pressure. Witnessing the factory acceptance test is justified whenever the assembly carries protection functions, the configuration is project-specific, or downstream rework would hit a schedule that cannot slip. For catalogue breakers or simple enclosures bought as commodities, a pre-shipment inspection is usually the right tier instead.
It becomes useful when
- LV or MV assemblies carry protection, metering or control functions that must demonstrably work before dispatch.
- The panels are project-engineered — custom schematics, project settings, project labelling — rather than catalogue items.
- Interlocks, earthing switches or racking mechanisms guard safety sequences that a certificate alone cannot prove.
- Relay settings and secondary-injection results must be on record before site cabling begins.
- The installation schedule cannot absorb fault-finding on arrival, or the site team is not the team that specified the panels.
- A lender, EPC or end client requires an independent factory-side record before release or milestone payment.
02 · Verification
What the witness controls in the panel shop
Control point
Test basis, drawings and readiness
Approved schematics, single-line diagram, settings file and the agreed schedule of tests confirmed before the visit; assembly completeness and instrument calibration references checked so the witness day is spent testing, not waiting.
Control point
Construction and wiring verification
Assembly checked against the approved drawings: component ratings and makes, busbar arrangement, clearances and creepage, point-to-point wiring on control and CT/VT circuits, terminations, ferruling and labelling.
Control point
Electrical routine tests witnessed
Protective-circuit continuity, insulation resistance and dielectric withstand witnessed with measured values recorded against the product standard and specification.
Control point
Mechanical operations and interlocks
Operating cycles, racking, earthing-switch operation and the interlock logic exercised through the defined sequences — including the sequences the interlocks must prevent.
Control point
Protection, control and documentation
Relay function proven by secondary injection where specified, control logic and alarms exercised by simulation, settings compared to the approved file; routine-test certificates, settings records and as-built markups reviewed before release.
03 · Evidence
Evidence captured during the witnessed FAT
- Test basis and readiness record
- Approved drawings, settings file, schedule of tests and acceptance criteria checked before the witness event.
- Assembly completeness, test instruments and calibration references, and responsible supplier personnel confirmed.
- Witness scope with exclusions documented — which functions are proven at FAT and which remain for site commissioning.
- Witnessed verification record
- Panel identity and construction photographed and tied to the record: nameplates, component makes and ratings, layout against drawings.
- Each witnessed test recorded with measured values, instrument references and pass/fail against the acceptance criterion.
- Wiring corrections, failed sequences and retests captured as they happen, with photo evidence where useful.
- Disposition and release record
- Non-conformities logged with severity, requirement reference, supplier response and re-verification status.
- Open items that do not block release carried forward explicitly with owners — never silently.
- Release, conditional release, hold or retest recommendation prepared for the buyer's decision.
04 · Deliverables
Deliverables issued
Deliverable
For · Procurement and engineeringWitness plan and readiness note
The agreed witness scope, drawing and settings basis, and readiness status before the visit.
Deliverable
For · Engineering, project and external reviewersSigned switchgear FAT witness record
Construction verification and witnessed tests with measured values and pass/fail status, tied to the panels on your order.
Deliverable
For · Engineering and operationsPhoto evidence pack
Labelled visual evidence of construction, wiring, test setups and corrected points, linked to the record.
Deliverable
For · Procurement and the supplierNon-conformity and re-verification log
Each wiring error, failed sequence or document gap classified, tracked through correction and re-verification.
Deliverable
For · Procurement and financeRelease recommendation
Release, release with comments, hold or retest — a written basis for the packing and payment decision that stays yours.
05 · Risks reduced
Risks this control closes
Risk
Wiring errors in control or CT/VT circuits ship inside a finished-looking cabinet and surface during commissioning.
How the witness closes it
Point-to-point verification against the approved schematics is witnessed and recorded before packing, with corrections re-verified on the spot.
Risk
Interlocks exist on the drawing but the built sequence does not actually prevent the unsafe operation.
How the witness closes it
Interlock logic is exercised through the defined sequences — including the prohibited ones — and the result is recorded, not assumed.
Risk
Relays arrive with factory-default or wrong settings and the error is found at energization.
How the witness closes it
Settings are compared to the approved file and protection function is proven by witnessed secondary injection where specified.
Risk
Dielectric or continuity tests are reported as passed without valid instruments or conditions.
How the witness closes it
Instrument references, calibration and test conditions are recorded with each measured value before it counts toward acceptance.
Risk
The FAT/SAT boundary blurs: everyone assumes the other test proved the function nobody tested.
How the witness closes it
The witness record states explicitly which functions were proven at FAT by simulation and which remain for site commissioning.
Risk
The buyer releases panels on a supplier's word and inherits fault-finding at site.
How the witness closes it
The signed witness record and release recommendation put the correction burden on the supplier while the panels are still in the shop.
06 · Background resources
Related
- Service · Factory acceptance test in ChinaThe parent FAT service: scope, control points and deliverables for any equipment class.
- Service · Transformer FAT witnessingThe sibling scope for power and distribution transformers on Chinese test bays.
- Service · PD test witnessing at FATThe specialist witness scope when partial discharge measurement decides acceptance of MV switchgear.
- Tool · Switchgear FAT checklist builderCompose a FAT checklist for LV/MV switchgear and control cabinets from a Chinese manufacturer.
- Resource · Factory acceptance test checklistThe twelve-section FAT checklist, downloadable as a printable PDF.
- Sector · EnergyHow Sinospect supports energy-sector buyers across supply, inspection and delivery.
07 · Questions
Frequently asked questions
Which switchgear and panel tests are witnessed during a FAT in China?
The witnessed scope follows your specification, single-line diagram and the agreed test schedule. For LV assemblies this typically covers the routine verification of IEC 61439: construction and wiring inspection against the approved drawings, clearances and creepage, protective-circuit continuity, insulation resistance and dielectric withstand, and functional tests of controls, metering and indication. For MV switchgear the routine tests of IEC 62271 apply, with mechanical operation, interlocks and voltage tests witnessed as specified. Protection relay checks by secondary injection are witnessed where your contract requires them.
Is a wiring check really worth an independent visit?
Wiring and configuration errors are the defect class most often discovered at site — after the panels are fixed to a wall, cabled and under schedule pressure. At the factory they are corrected in hours. A witnessed point-to-point and functional check against the approved schematics converts "the drawings were followed" from an assumption into a record.
What happens if the assembly fails a witnessed test?
Each failure is recorded as a non-conformity with the requirement reference and the supplier's response, and the corrected point is re-verified before the record closes. Failures that touch safety — protective continuity, dielectric withstand, interlocks — normally support a hold recommendation until the retest passes. You keep the release decision.
Can functional tests be witnessed when the site systems aren't available?
Yes — that is normal at FAT. Control and protection functions are exercised by simulation: secondary injection for relays, forced signals for I/O, test supplies for control circuits. The witness record states which functions were proven by simulation and which remain for site commissioning, so the boundary between FAT and SAT stays explicit.
Does this cover control cabinets and automation panels, not just switchgear?
Yes. The same witness structure applies to control cabinets, MCCs, automation and instrumentation panels: construction against drawings, wiring verification, insulation and continuity checks, then witnessed functional simulation of the control logic, alarms and interfaces defined in your specification.
08 · Getting started
What to send — start with what you have
Approved drawings are the ideal starting point, but a specification or even the supplier's quotation is enough for Sinospect to propose the witness scope.
Single-line diagram and schematics
The approved drawings the assembly must match — the basis of the construction and wiring verification.
Specification or schedule of tests
The tests and acceptance criteria the contract requires, if already defined.
Settings file, where protection applies
Approved relay settings so witnessed secondary injection proves the right values.
Purchase order and panel-builder details
What was ordered and where the shop is, so the visit can be arranged.
Expected test-readiness window
When the builder expects the assembly complete, so witnessing lands before packing.
Partial information is fine. Sinospect confirms what is usable, what is missing and what it changes before any commitment.
Book an independent witness for your switchgear FAT
Send the drawings or specification, the panel builder and the expected test window. Sinospect replies within one business day with the proposed witness scope, a quotation and the earliest feasible attendance — or tells you plainly if a pre-shipment inspection fits the order better.