Quick answer
A compact substation RFQ should show the external earth grid, internal earth bar, enclosure and door bonds, transformer tank and neutral connections, MV cable screens, LV protective conductors, auxiliary equipment and test points. Separate protective bonding from system earthing and functional or communications connections. The package supplier, civil contractor, cable installer and owner must each be named against a drawing and an acceptance test.
Why earthing becomes a package boundary
A compact substation combines an enclosure, medium-voltage equipment, a transformer and low-voltage equipment in a constrained footprint. Several contractors may deliver the foundation, earth grid, cables, package, control wiring and site tests. A quotation that says “earthing included” does not say whether it includes the internal bar, external conductor, cable-screen bonds, transformer neutral, test links, lugs, clamps or site measurements.
Use the Compact Substations page to identify the Jinxing package family, then mark every connection on the project single-line, earthing and general-arrangement drawings. Final conductor sizes, fault duty, touch or step criteria and local requirements must come from the approved project design.
Separate the earthing functions
Use clear labels so the same connection is not assigned to two different owners.
| Function | Project question | Evidence to request |
|---|---|---|
| Protective bonding | Which exposed metal parts must be bonded to the internal earth bar? | Bonding drawing, bar schedule and continuity test plan |
| System earthing | Where are the transformer neutral or system reference connections made? | Earthing study, single-line and approved neutral arrangement |
| MV cable screens | Who bonds, terminates, insulates or tests each cable screen and sheath? | Cable schedule, termination detail and test responsibility |
| LV protective conductors | Where do PE conductors, equipment earths and incoming earths terminate? | LV panel drawing, terminal schedule and site connection detail |
| Enclosure and doors | Which doors, covers, roof, partitions and removable parts require flexible bonds? | General arrangement and inspection checklist |
| Auxiliary and control circuits | Which control, battery, communications or shield connections have special rules? | Auxiliary schematic, interface matrix and commissioning record |
| External earth grid | Who supplies conductors, rods, joints, test links and site measurements? | Civil/earth-grid drawing and accepted site test record |
The table is a procurement framework, not a default Jinxing configuration. The engineer must confirm the applicable earthing method and the supplier must identify the delivered terminals and hardware.
Draw the internal-to-external boundary
Mark the physical handover point. It may be an earth bar inside the enclosure, a pair of external terminals, a foundation connection, a cable trench or a test link. For every boundary, record the mating conductor, lug or clamp, installation owner, drawing reference and test record.
The existing compact substation equipment supply boundary guide covers civil works, cables and control interfaces. This article narrows the earthing portion so a buyer can ask who provides the bar, bond, cable-screen connection and measurement. The compact substation foundation checklist should be reviewed with the earth-grid route, openings, drainage and fixing details rather than after the package drawing is frozen.
Coordinate transformer, MV and LV connections
The transformer tank, core or neutral arrangement, MV switchgear earth points and LV panel PE/N arrangement must use consistent names. If the transformer neutral is brought out, state whether it is connected at the package, at the downstream board or by another contractor. If the package has a ring main unit, identify the cable-screen and earth-switch interfaces on the same schedule.
Auxiliary power also needs a defined earth reference. The compact substation auxiliary power boundary guide can help identify control, lighting, heating, communications and source responsibilities. Do not assume that an auxiliary supply schedule proves the protective-conductor or communications-bonding arrangement.
Make testing and handover traceable
Ask for the drawing and document register before manufacture. At minimum, align the general arrangement, single-line, earthing drawing, earth-bar schedule, cable termination details, auxiliary schematic and final as-built pack. Define which tests are factory checks and which require site access or an earth-grid measurement.
The acceptance record should identify the equipment serial or package reference, test point, method, result, instrument or responsible tester where the project requires it, and any open deviation. A factory continuity check does not automatically prove the completed site earth grid or external cable-screen installation.
RFQ checklist
Include the following with the compact substation enquiry:
- Single-line, earthing study or design basis, transformer neutral arrangement and applicable owner rules.
- External earth-grid drawing, electrode or grid interface, test links, joints and civil route.
- Internal earth bar location, cross-bonds, enclosure, doors, roof, partitions and removable equipment bonds.
- MV cable screens, terminations, earth switches, transformer tank or neutral, and LV PE/N connections.
- Auxiliary, control, communications and shield-bonding interfaces with named responsibilities.
- Foundation openings, cable trenches, drainage, access and protection of the earth connection during installation.
- Required factory checks, site continuity or earth-grid tests, inspection points and acceptance limits.
- GA, earthing, terminal, cable, auxiliary, test, packing and final as-built documents.
- Quantity, destination, package type, project stage and unresolved engineering decisions.
Review the Compact Substations product family and submit the marked scope through Request a Quote. Final earthing arrangement, conductor ratings and acceptance criteria remain project-specific.
FAQ
Is the compact substation earth bar part of the package price?
It may be, but the quotation must state the bar, hardware, internal bonds, external terminals, cable-screen connections and site work separately. “Earthing included” is not enough for a comparable offer.
Who connects the transformer neutral to earth?
The project earthing design must decide where the system connection is made and how it is protected, switched or monitored. The package supplier should show the offered terminal and responsibility; the installer should not infer it from the enclosure drawing.
Does a factory continuity test prove the site earthing is complete?
No. Factory checks cover the tested package boundary. The external grid, foundations, cable screens and final site connections need the project-defined inspection and measurement records.