BOQ and quota item selection for compact package unit substations (prefabricated substations): the mainstream principle of billing the complete unit per set; splitting into transformer plus HV/LV panels only for non-package supply, missing quota bands or contract-required splits; with commissioning and handover-test interfaces and a Beijing / Shenzhen / railway / national-standard comparison

Topic Positioning

Quota item selection, BOQ billing and measurement conventions for compact package unit substations (prefabricated substations, including American- and European-style package units): establishing billing of the complete unit as the mainstream principle, sorting out when a split into transformer plus HV/LV panels billed separately is legitimate, and giving the treatment of the commissioning, handover-test, excluded-content and equipment-cost interfaces. Applicable to rate build-up under the building-electrical (Beijing), municipal (Shenzhen), railway and other quota systems.

Core Conclusions

1. Overall convention: bill the complete unit (mainstream principle)

• Beijing DB11/T 2382-2024 clause 6.4.19 (original text): "The installation of compact package unit substations shall set the corresponding item with one container body as one unit. Quantities are computed as the number shown on the design drawings."
• The Beijing items sit in Annex C table C.4.10 "installation of compact package unit substations", banded by capacity (kVA and below) with unit of measurement "set", e.g. C4-2-21 for the 2000kVA band; work content: "unboxing, checking and counting, positioning, aligning, fixing, wiring and checking, equipment adjustment, interlock checks, conductor contact-surface checks, secondary element removal and refitting, earthing, touch-up painting, individual commissioning etc."; plant configuration includes the high-voltage test transformer, DC high-voltage generator, dissipation-factor meter, transformer ratio tester and transformer DC-resistance tester - individual commissioning is already absorbed in the installation item, and no further transformer or HV-panel items are applied.
• Railway TB/T 10829-2024 Volume 8 Power Works: installation items DY-1074 to DY-1081 (per unit, capacity bands from not over 1x500 to not over 2x1250), in-tunnel installation separately DY-1082 to DY-1084, work content "visual check on unboxing, installation and fixing, wiring, earthing"; commissioning is a separate item - DY-1407 to DY-1410 "package unit substation commissioning" (per unit; work content: HV and LV insulation tests, functional and earthing-continuity tests), plus package reactor commissioning (DY-1411) and package switchroom commissioning (DY-1412 to 1413). That is, the railway convention is installation plus commissioning as two items, likewise without splitting the body.
• Shenzhen SJG 181.7-2024: "Installation of HV switchgear assemblies and compact package unit substations shall be computed per set as the number shown on the design drawings."
• BOQ measurement GB/T 50856-2024: under switchgear installation (code 030402) sits the item "prefabricated substation", whose structural forms include American- and European-style package units (D.17.5 explanatory note item 9); clause 3.0.11: "The equipment installation work content in this standard includes commissioning of the equipment itself and no-load trial runs." - commissioning of the equipment itself is in principle not billed again. Scope: installation works of 10kV-and-below transformation and distribution equipment and lines (D.17.1).

2. When a split is legitimate (four cases) (1) Non-package equipment - HV panels, transformer and LV panels supplied and installed separately (renovation or non-standard works with no package unit to apply); (2) Missing quota band - beyond the current capacity bands and not convertible; handled by borrowing similar quota items or compiling supplementary quota items (supplementary unit-rate build-up schedules); (3) The employer or the contract requires equipment and installation to be billed separately, priced unit by unit per the equipment schedule; (4) Excluded content billed separately - e.g. SJG 181.7-2024 states expressly: installation of compact package unit substations "does not include fabrication of supports and foundation steel channels, fabrication and installation of busbars and drop-out leads and installation of equipment components, and external wiring of terminal blocks; where these occur, the corresponding items apply"; package substation foundations, cables and the like are billed separately under the relevant chapters.

Red line: split or unsplit - one of the two. Unboxing, checking, positioning, fixing, wiring and checking, earthing, commissioning of the equipment itself and other included content must not be borrowed back against the complete-unit item; conversely, the complete-unit item must not be charged for content already split out - strictly no double counting at both ends.

3. Equipment cost and material interface The installation items' consumptions cover only auxiliary materials such as spacer plates, galvanised bolts, flat steel and welding electrodes, plus lifting and test plant; the package substation product itself is carried as unpriced equipment (material) and billed separately.

4. Billing and execution of commissioning and handover tests

• Beijing convention: individual commissioning is included in the work content of installation items such as C4-2-21; railway convention: commissioning is a separate item (DY-1407 to DY-1410); GB/T 50856-2024 clause 3.0.11: equipment installation work content includes commissioning of the equipment itself and no-load trial runs.
• Handover tests: TB 10420-2018 clause 5.16.3 - "package unit substations and package reactors shall undergo handover tests, and their main electrical performance check items and requirements shall comply with GB 50150 'Standard for Handover Tests of Electrical Equipment, Electrical Equipment Installation Works'"; checking: fully checked by the contractor, witnessed by the supervising engineer; method: tested by a qualified testing institution with the supervising engineer in attendance.
• GB 50303-2015 clause 4.1.6: for package substations composed of three independent units - HV switchgear assemblies, LV switchgear assemblies and the transformer - the HV part shall pass the handover tests per clause 3.1.5; for package substations with HV switches, fuses etc. combined with the transformer in one sealed oil tank, handover tests follow the product technical documents; "the phase-to-phase and phase-to-earth insulation resistance of every distribution switch and protection device of LV switchgear assemblies and feeders shall not be less than 0.5 megohm; where current national product standards are silent, the power-frequency AC withstand test voltage shall be 1000V for a duration of 1 minute; where the insulation resistance exceeds 10 megohm, a 2500V megger should be used." Checking: all; method: insulation-resistance testing plus review of the handover test records.
• DB62/T 3030-2018 clause 4.6.5, same convention: for package substations composed of three independent units - HV and LV switchgear assemblies and the transformer - the HV part undergoes handover tests per GB 50150 and passes; for package substations with HV switches and fuses combined with the transformer in one sealed oil tank, handover tests follow the manufacturer's technical documents.

Applicability Boundaries

• Applicable to installation works of 10kV-and-below transformation and distribution equipment and lines (scope of GB/T 50856-2024 Annex D) and to rate build-up of package substations in the building-electrical, municipal and railway disciplines.
• Item numbers and capacity bands vary by standard edition, sector and region; the Beijing (DB11/T 2382-2024), Shenzhen (SJG 181.7-2024) and railway (TB/T 10829-2024) numbers cited here only locate the corresponding chapters - before applying, check the current consumption standard and edition of the project's locality; item numbers must not be transplanted across systems.
• Splitting is limited to special cases such as non-package supply, missing quota bands and contractual agreement, mutually exclusive with complete-unit billing, strictly no double counting.
• Handover tests and acceptance follow GB 50150, GB 50303-2015, TB 10420-2018 and the corresponding standards; the interface between test costs and installation items follows the notes of each local quota manual.
• This card does not deal with specific equipment prices and is not a conclusion on the settlement of any particular project.

Further Reading

• DB11/T 2382-2024 "Consumption Standard for Construction Works", section 6.4.III switchgear installation (6.4.12 to 6.4.20), Annex C table C.4.10 (items C4-2-21 etc.)
• SJG 181.7-2024 "Consumption Standard for Municipal Works, Volume 7, Power Ducts, Telecommunication Ducts and Lighting Works", 2.1.7 and 2.2.2
• TB/T 10829-2024 "Railway Works Budget Quota, Volume 8, Power Works", chapter 9 section 2 package unit substation installation (DY-1074 to DY-1084), electrical system commissioning DY-1407 to DY-1417
• GB/T 50856-2024 "Standard for Method of Measurement of General Building Services Installation Works", table D.2.1 (code 030402), D.17.1, D.17.5 and clause 3.0.11
• GB 50303-2015 "Code for Acceptance of Construction Quality of Building Electrical Engineering", clauses 4.1.6 and 3.1.5; GB 50150 "Standard for Handover Tests of Electrical Equipment, Electrical Equipment Installation Works"
• TB 10420-2018 "Standard for Constructional Quality Acceptance of Railway Power Works", section 5.16 (package unit substations and package reactors); DB62/T 3030-2018 "Construction Technology Regulation for Building Electrical Engineering", 4.6.5