Visual and dimensional inspection finds errors that electrical tests can miss: wrong components, blocked pressure paths, inaccessible terminals, sharp edges, label mismatches and cable-space conflicts.
Learning objectives
Create an objective inspection checklist tied to approved drawings and product evidence.
Core engineering principles
Construction must match the qualified design
Partitions, ducts, relief flaps and supports should not be changed casually because they influence thermal, short-circuit and internal-arc performance.
Component identity includes full rating
Model, voltage, current, auxiliary supply and accessory code must match BOM and schematic.
Dimensions include interfaces
Panel width and height are insufficient; cable entry, termination height, door swing and transport split matter.
Workmanship affects reliability
Wire routing, edge protection, hardware locking, labels, clearances and cleanliness are inspected.
Access and operation are part of inspection
Doors, shutters, racking handles and test points should be usable without interference.
Engineering application method
- Step 1: Inspect against approved GA, section and BOM.
- Step 2: Measure critical dimensions and interface locations.
- Step 3: Verify component nameplates and quantities.
- Step 4: Check workmanship, labels and access.
- Step 5: Record defects with location, photo and disposition.
Practical example
A correct CT ratio is still unusable if cable bend radius blocks the secondary terminal or a gland plate prevents installation. Dimensional review catches the interface failure.
Common mistakes
- Inspecting only external appearance.
- Accepting substitute components by brand similarity.
- Ignoring pressure relief clearance.
- Leaving measurement tolerance undefined.
- Recording defects without exact panel location.
Design and review checklist
- Does construction match approved drawings?
- Are all ratings correct?
- Do cable and building interfaces fit?
- Is workmanship acceptable?
- Are defects traceable to resolution?
Standards basis and official sources
- IEC 62271-200:2021 + AMD1:2024 — AC metal-enclosed switchgear assemblies above 1 kV and up to 52 kV.
- IEC 62271-100:2021 + AMD1:2024 — Alternating-current circuit-breakers.
- IEC 61439-1:2020 — General rules for low-voltage switchgear and controlgear assemblies where applicable.
Engineering note: Verify the contracted standard edition, amendments, manufacturer evidence and project-specific studies before applying these principles to a supplied assembly.