Same incomer. Different project.
Consider two illustrative 1,600 A main switchboards. Board A distributes power to six submains in a dedicated indoor switchroom. Board B serves twenty outgoing circuits and includes a second supply, a coupler, networked metering and a more complex operating sequence. Even before selecting a platform, they represent different quantities of equipment, connections, drawings and tests.
Board A: distribution duty
One supply, a short outgoing schedule and a clearly defined indoor location. The quotation still needs a fault rating, enclosure requirements and cable details.
Board B: multiple interfaces
Two supplies, more circuits and a documented control sequence. The scope must resolve interlocking, operating modes, protection and additional acceptance tests.
These are scope examples, not CWS quotations or a recommendation for a particular supply arrangement. They show why a price per amp, or a price copied from an unrelated project, is a weak basis for a capital budget.
For a motor control centre, the difference can be greater still: twenty small DOL feeders and twenty drive feeders are not comparable simply because both boards serve twenty motors.
The six parts of the cost ledger
| Cost area | Information that changes the offer | Useful budget question |
|---|---|---|
| Power circuits | Incomers, couplers, outgoing quantities, ratings and specified devices. | Have all circuits been scheduled, including auxiliaries? |
| Assembly construction | Supported platform, separation, dimensions, access and cable compartments. | Does the required layout fit the actual room and cables? |
| Fault and protection duty | Supply fault data, assembly rating and the coordinated protection scheme. | Are the fault assumptions and protection responsibilities agreed? |
| Controls and visibility | Metering, relays, PLC interfaces, signals and communications. | Which functions must be supplied, wired and demonstrated? |
| Engineering and verification | Drawings, design evidence, routine verification, FAT and handover records. | What must the manufacturer deliver at acceptance? |
| Delivery and site interfaces | Transport sections, packing, lifting data, installation and changeover boundaries. | Where does the factory supply scope finish? |
On smaller screens, scroll the table sideways to see all columns.
A higher component price is not the only way scope grows. A restricted cable-entry zone may require a wider section. A late change to the motor schedule may alter the layout, protection selection, heat assessment and drawings together. Budget risk often sits in unresolved interfaces rather than in a single expensive breaker.
Separate the assembly’s short-circuit capability from the breaking capacity marked on an individual protective device. Ask for the proposed assembly rating and the basis supporting it; a component selection does not establish every characteristic of the complete board. [source]
Use the right price for the stage of design
Concept allowance
Record the assumed board type, circuit count, environment and exclusions. Identify open decisions and use a clearly stated validity period. This is a planning allowance.
Developed budget
Update the single-line diagram and schedules. Identify equipment preferences, interfaces and delivery requirements. Resolve the largest uncertainties before comparing options.
Detailed quotation
Price an agreed revision and describe departures, exclusions and validity. Changes after acceptance follow an agreed variation and drawing-control process.
Keep three amounts separate in the project budget: the switchboard manufacturing package, site electrical works, and other project works such as building alterations or civil work. Freight, cranage, commissioning and studies should have an owner even when they are excluded from the board quotation.
Avoid adding an unexplained contingency and treating the result as a fixed price. Keep a short assumptions register: the uncertainty, its effect, who will resolve it and the date needed.
Where a budget can be improved
The best alternative is one that changes scope deliberately while retaining the required performance. Examples include removing duplicated metering, clarifying whether a packaged machine already includes its starter, choosing a supported standard arrangement, or providing a future feeder space instead of a fully populated feeder when that genuinely meets the expansion plan.
Ask the manufacturer to price alternatives against the same duty and show the consequences. A smaller enclosure is not a saving if it compromises cable termination space or requires a different thermal solution. A reduced testing scope is not an acceptable substitution for required routine verification.
- Confirm what free-issued equipment includes and who checks its suitability.
- Freeze the major equipment and cable interfaces before final layout approval.
- Separate essential operational requirements from preferences that can be evaluated as alternatives.
- Compare lifecycle implications such as spares, access and replacement tasks as well as the purchase price.
Make the edition part of the brief
For a new industrial assembly, identify the relevant AS/NZS 61439 part and edition in the quotation request. The 2026 catalogue editions of Parts 1 and 2 are available; specify the intended basis explicitly rather than using an undated reference. [source] [source]
What to send for a useful budget
Send the concept single-line diagram, circuit or motor schedule, supply information and a description of the environment. Include the space available, cable-entry direction, delivery destination and required programme. Label unknowns clearly; a recognised gap is easier to price and resolve than an untested assumption.
Our switchboard enquiry guide covers the documents in more detail. For procurement comparisons, use the manufacturer and quotation comparison guide.
Sources and further reading
Sources checked 30 September 2026. Examples are identified where illustrative. Confirm the applicable project standards, editions and manufacturer instructions.