A useful switchgear quotation starts with a coordinated document package. The single-line diagram (SLD) shows how power flows through the system, the bill of quantities (BOQ) defines the requested supply items, and the technical specification states the construction, performance and documentation requirements. When these files agree, an EPC contractor receives a clearer technical proposal and fewer clarification questions.
What should each RFQ document contain?
| Document | Main purpose | Important information |
|---|---|---|
| SLD | Defines the electrical topology and source-to-load arrangement | Sources, incomers, bus sections, couplers, feeder ratings, protection and metering |
| BOQ or cabinet schedule | Defines the equipment and quantities to be quoted | Panel references, quantities, ratings, feeder ways, accessories and spare requirements |
| Technical specification | Defines construction and project requirements | Applicable standard, IP rating, separation, components, testing, drawings and packing |
| Room or site information | Defines installation constraints | Dimensions, access, cable entry, ambient conditions, altitude and destination |
Step 1: define the electrical system basis
State the rated system voltage, frequency, number of phases, earthing arrangement and auxiliary control voltage. Identify whether the system is supplied by a utility transformer, generator, UPS, renewable source or a combination of sources. Do not leave the source arrangement to be inferred from the cabinet names.
Step 2: make the SLD technically readable
Show every incomer, bus section, bus coupler and outgoing feeder that belongs to the requested scope. Each circuit should have a unique reference. Where ratings are known, add the protective-device rating, load description, cable information and metering requirement. Clearly mark future feeders, spare ways and equipment outside the supplier scope.
Minimum information to show on the SLD
- Source type, quantity and normal operating condition
- Rated voltage, frequency and fault level at the assembly
- Incomer, coupler and outgoing feeder ratings
- Load names and feeder references
- Protection, metering and communication functions
- Normal, emergency and standby operating sequence
- Equipment and interfaces excluded from the quotation
Step 3: align the BOQ with the SLD
Every panel and feeder reference in the BOQ should match the SLD. Avoid a BOQ that lists only “one set switchgear” without identifying the section count or feeder arrangement. For each assembly, state the quantity, rated current, short-circuit requirement, enclosure protection and any preferred component make.
Recommended BOQ columns
| Reference | Description | Rating | Quantity | Required options |
|---|---|---|---|---|
| MDB-01 | Main distribution board | Project value | 1 set | Metering, cable entry, spare feeders |
| MCC-01 | Motor control centre | Project value | 1 set | Motor schedule and control interfaces |
| DB-L1 | Final distribution board | Project value | Project quantity | Circuit schedule and mounting method |
The values above are document examples, not recommended electrical ratings. Actual ratings must come from the approved project design.
Step 4: add the site and construction requirements
State indoor or outdoor installation, ambient temperature, altitude, humidity, dust or corrosion conditions and the required degree of protection. Include room dimensions, access limitations, cable-trench position and top or bottom cable entry. These items can change cabinet depth, ventilation and section arrangement.
Step 5: define components, inspection and documents
List approved breaker, contactor, meter, relay and controller brands where the project has a vendor requirement. State the applicable IEC standard and the drawings, component schedules, routine inspection records, manuals and packing documents expected with the order. Review the IEC 61439 EPC procurement checklist when preparing a low-voltage assembly specification.
Match the document package to the equipment type
- PCC switchgear: source data, feeder schedule, fault level and bus arrangement
- MCC: motor list, starting methods, control philosophy and interlocks
- ATS panel: source priorities, transfer sequence, neutral treatment and generator signals
- APFC panel: load profile, existing and target power factor, and harmonic data
- Main distribution board: incoming supply, outgoing schedule, metering and room constraints
- Final distribution board: circuit schedule, protection type, spare ways and mounting method
- Custom enclosure: dimensioned drawing, component layout, material and environmental requirement
Common RFQ problems to avoid
- Different feeder references in the SLD and BOQ
- Missing system fault level or short-circuit requirement
- No distinction between fixed, withdrawable or transfer functions
- Unclear cable entry and room-access restrictions
- Brand requirements listed without exact series or approved alternatives
- Old drawing revisions included in the same RFQ package
- Testing and document requirements added only after pricing
Use one controlled RFQ package
Give each file a clear revision and date, remove superseded drawings, and include a short document register. If information is not yet available, mark it as “to be confirmed” instead of leaving conflicting values in different files. For an industrial package, review the industrial-facilities solution; for building distribution, review the commercial-buildings solution.
Frequently asked questions
Can I request a quotation without a complete BOQ?
Yes. Send the available SLD and load or feeder schedule first. The missing commercial and technical items can be listed during the initial review.
Is a cabinet model name enough for pricing?
No. A model reference does not define the feeder arrangement, fault level, protection, enclosure, components or documentation required for the completed assembly.
Should DWG and PDF versions both be provided?
A controlled PDF is useful for review, while an editable drawing can support engineering coordination. Both files should carry the same revision and technical information.
Send the controlled documents for review
Zejiefu reviews the submitted SLD, BOQ and specification to identify equipment boundaries and missing inputs before a project-based quotation is prepared.
BOQ and RFQ are different documents
For procurement terminology and document responsibilities, read BOQ vs RFQ for electrical switchgear projects.
Coordinate the APFC capacitor bank data
Where reactive-power compensation is included in the package, provide the existing and target power factor, load profile, required kVAr and harmonic information. Review the APFC capacitor-bank selection inputs before issuing the RFQ.