What Overseas Buyers Should Include in a Main Distribution Board RFQ

A request for a main distribution board (MDB) can look complete while leaving out the details that determine the final cabinet arrangement. A short description such as “400 V, 1,600 A MDB” identifies the broad requirement, but it does not tell a manufacturer how many outgoing circuits are needed, what fault level to design for, or how the cables will enter. When these points are clarified early, buyers can compare quotations on the same basis and reduce revisions after an order is placed.

Start with the electrical system, not the enclosure

The most useful starting document is a single-line diagram. It shows the sources, incomers, bus coupler if any, outgoing feeders, and the relationship between the MDB and downstream boards. A feeder schedule adds each circuit’s rating and load description. If these documents are still being prepared, a buyer can send a preliminary circuit list and identify which values are provisional. That is more useful than leaving important fields blank and assuming every supplier will make the same interpretation.

The quotation should state the system voltage and frequency, rated current, and the prospective short-circuit level at the board. The required short-circuit performance must be checked against the proposed busbar, protective devices, and assembly. A breaker’s individual rating should not be treated as proof that the complete assembly meets the project requirement. The applicable standard, inspection scope, and supporting documentation should be agreed for the actual configuration.

Make physical constraints visible

An MDB is also a space-planning decision. Provide the available room dimensions, access clearances, cable entry direction, and any limitations on lifting or moving sections into place. If a project requires future circuits, specify whether it needs only empty space or a complete provision for additional feeders. Those are different scopes with different costs.

The enclosure’s protection level, internal separation, ventilation, and installation environment should follow the project specification. A cabinet for a conditioned electrical room may require a different arrangement from one exposed to heat, dust, or frequent washdown. The buyer should describe the actual site conditions rather than selecting an enclosure label in isolation.

Compare quotations line by line

Price comparisons are meaningful only when the offered scope is visible. Ask each supplier to identify the incomer and feeder devices, their specified brands or approved alternatives, the busbar arrangement, spare capacity, metering, cable termination space, and documentation included. Record exclusions and open points. A low initial price can reflect a genuine design choice, but it can also reflect an omitted item that appears later as a variation.

Buyers can review main distribution board configuration options as a starting point for discussing a project-specific arrangement. The final bill of materials, ratings, dimensions, and documents should still be confirmed against the project drawings and technical specification.

Give the supplier a clear next step

A practical RFQ does not need to be perfect on day one. Send the current single-line diagram or circuit list, the target ratings, site conditions, and the required delivery destination. Mark uncertain values clearly and ask the supplier to return a list of assumptions and questions alongside the quotation. This turns the first exchange into an engineering review rather than a price guess.

For overseas projects, it also helps to state the destination country, preferred Incoterm, required document language, and any project-specific approval process. These details affect the commercial offer and the document package even when the electrical design is similar. Wenzhou Zejiefu Electrical Equipment Co., Ltd. discusses project requirements and proposed cabinet configurations with buyers before the final scope is confirmed.

The best MDB RFQ is therefore not the longest one. It is the one that makes the electrical duty, physical constraints, and open decisions clear enough for suppliers to price the same job.